TORRO's research into lightning impacts in the UK
Since the 1970s, TORRO has compiled a national database of incidents when lightning has struck people, buildings, property, trees and animals and disrupted electricity supplies. This has enabled an assessment of the lightning risk in the UK to be undertaken and to compare this risk with other countries. Lightning safety advice is provided to organisations and the media. Research into specific incidents is undertaken too. Summaries and reviews of each year's lightning incidents are published in the International Journal of Meteorology along with annual summaries of thunderstorm activity. Copies of the most recent reviews are available from Derek Elsom and/or Jonathan Webb.
If you have experienced a lightning incident, please help TORRO's research and send details to Professor Derek Elsom at email@example.com and/or Jonathan Webb at firstname.lastname@example.org
The scope of TORRO's research into lightning impacts is summarised by Derek Elsom and Jonathan Webb in chapter 10 of 'Extreme Weather: Forty Years of the Tornado and Storm Research Organisation', edited by Robert K. Doe, Wiley-Blackwell, 2015.
Lightning seen from Charmouth, Dorset, on 22nd July 2013 (© Matthew Clark)
Number of fatalities and injuries
Analyses of lightning fatalities over the past 25 years in the UK shows that, on average, two people are killed by lightning each year and around 30 people injured. Prompt resuscitation of people who have suffered cardiopulmonary arrest due the electric shock of a lightning strike has, on average, prevented another death each year.
Fuller details are available in the article by Elsom and Webb (2014):
Deaths and injuries from lightning in the UK (ResearchGate Version)
Deaths and injuries from lightning in the UK (PDF Version)
The number of people injured is an underestimate as some people don't bother to report their lightning experience if the electric shock left them with simply tingling arms and temporary numbness of the legs which wore off after an hour or so.
The average annual fatality and injury figures above refer only to those experiencing an electric shock from lightning. They exclude other people who may have been injured indirectly such as by smoke inhalation and burns from fires started by lightning, from being struck by roof tiles and masonry dislodged from a building struck and damaged by lightning, and being struck by tree bark ejected explosively when lightning strikes a tree and vapourises the sap.
Total number of significant lightning incidents
TORRO maintains a record of the annual total number of reported incidents in the UK of lightning affecting people (both directly and indirectly), houses and other buildings, property, trees, animals and electricity supplies. This total is based on news and social media reports as well as TORRO's network (and other networks such as the Climatological Observers Link) of national weather observers who send in details of lightning incidents in their area. Although there may be many minor incidents which go unreported, the variation in the number of significant lightning incidents each year is highlighted below with 2006 being a particularly harsh year:
What is lightning and thunder?
Lightning is a huge electrical spark (discharge) that flows from a cloud (called a cumulonimbus or thunderstorm) to the ground, or within and between clouds, or from the cloud to air. Thunder is the sound produced by the rapid heating of the air by a lightning flash. The air expands explosively and contracts rapidly, producing sound waves.
The UK Meteorological Office provides useful resources to explain how thunderstorms, lightning and thunder form:
There are many US websites which explain the science as well as lightning safety:
Where in the UK is the greatest risk of being struck and when?
Thunderstorms may occur in any part of the UK and in any month although southeast England and the summer half year, especially the months of May to August inclusive, give rise to the highest incidence of thunderstorms and resulting lightning. Although there is significant annual variability in the occurrence of thunderstorms, the map below highlights the long-term annual number of thunder days for the 30-year period 1981-2010. However, there are some limitations of the 'thunder days' statistic as discussed by the following articles (contact Jonathan Webb for further details):
Prichard, R. J (1985) The spatial and temporal distribution of British Thunderstorms. J. Meteorology, UK, 10, 227-230.
Webb, J. D. C (2014) Thunderstorm Division review for Britain and Ireland 2013. Int. J. Meteorology, UK, 39, 135-140 (section 5).
Under 5 Days
Potentially dangerous cloud-to-ground strikes make up only one-quarter of all lightning generated by thunderstorms. Most other lightning happens wholly within the cloud and is visible only as a brightening of the cloud (often called 'sheet lightning').
Each year the United Kingdom, Ireland and the surrounding seas typically experience 200,000 to 300,000 lightning counts. A 'thunderstorm day' may experience as many as 10,000 but on exceptional days more than 50,000 can occur, as happened on 28 June 2012 when there were 64,000 strikes.
Lightning effects on the human body: immediate and short-term
Although lightning is a potentially lethal high-voltage electric current, it has contact with a person for only milliseconds unlike the longer lasting and continuous current experienced if someone touches a bare wire of an indoor electrical circuit or an outdoor power cable.
The short-lived electric current of a lightning strike may simply pass over the surface of a person's skin or clothes without most of it penetrating the body. This 'flashover effect' explains why some people experience minor injuries only. Indeed, often and contrary to popular belief, many people who experience a lightning strike suffer no burns.
For further information, refer to the extensive review of 'lightning injuries' by Professor Mary Ann Cooper, Christopher J. Andrews and Ronald L. Holle, a chapter in Paul C. Auerbach (ed.), Wilderness Medicine, 2007, 5th edition:
Unfortunately, there are occasions when a large amount of the current penetrates the skin causing serious burns and major damage to internal organs such as the heart, lungs and brain, which may lead to cardiopulmonary arrest and death. Only cardiac and respiratory arrest causes immediate death, not burns.
When someone is struck, the electrical current may follow a line of sweat, as a moist skin surface is a better conductor than adjacent dry areas of skin. The heat generated by the current may cause this moisture to superheat and vapourise (turning to steam), causing minor or superficial burns to the sweaty parts of the body. If such sudden explosive vapourisation takes place on sweaty feet in the confined space of tight-fitting footwear then socks may be ripped and footwear torn apart.
The eyes are especially sensitive to electric currents and heat so can be damaged if a person is struck by lightning or suffers the effects of a close lightning strike. Cataracts may develop many months or even a year or so later.
Being close to a lightning strike is like being near to an explosion. Ear drums may be ruptured. The shock or pressure wave can throw people to the ground causing blunt trauma injuries and even loss of consciousness for a while. Within 10 to 20 metres of a strike, the electric current spreading out from the strike point may pass up one leg and down the other, causing the leg muscles to involuntary contract and throwing that person violently to the ground. Temporary paralysis of the legs and sometimes the arms may occur which may take several hours to wear off. People struck may be disoriented and confused for several hours.
Flashover effects may leave to reddish fern-like pattern on the skin called a Lichtenberg figure, named after a scientist who first described the pattern. It is caused by electrons being driven into the epidermis which radiate outward from successive points in a fractal pattern of repeated bifurcations. Not everyone struck by lightning has this pattern. It doesn't appear until half an hour or several hours after the lightning strike and disappears within a few hours to 48 hours. It is not a burn and leaves no lasting effects but it is a tell-tale sign that the person was struck by lightning.
Right is the Lichtenberg figure on the arm of a 10-year-old girl struck by lightning at the window of her home in Merthyr Tydfil, south Wales in May 2011:
Lightning effects on the human body: long-term or permanent
Some people who survive a lightning strike may suffer long-term or even permanent health problems. These may be wide-ranging from sleep, concentration and memory problems, post-traumatic stress disorder (PTSD), depression, irritability, eye damage and cataracts, and chronic pain. In rare and extreme cases, damage to the brain may be so severe that they need round-the-clock medical care.
Some people who experience long-term problems as a result of a lightning strike may not have suffered any serious injuries at the time of the strike. Only days, weeks or months later have behavioural and psychological problems developed.
The Lightning Strike and Electric Shock Survivors International (LSESSI) in the US is a non-profit support group run by, and for, survivors and their families from across the world:
Lightning myths about being struck by lightning
Carrying or wearing small metal objects (e.g. necklace, bracelet, ring, earrings, body piercing stud, belt buckle, underwired bra, keys) does NOT make that person more likely to be struck. Rather, the objects may cause burns, sometimes in the shape of the object, on those parts of the body they are in close contact with because the metal heats up rapidly to very high temperatures. Very thin metal objects, such as a necklace, may even be vapourised.
Metallic and plastic mobile phones and smartphones do NOT attract lightning and nor do the electromagnetic waves used for communication. However, wearing ear phones or placing the mobile phone against the ear may result in burns around the ear and cheek if that person is struck. Some, but not all, researchers suggest they may disrupt the flashover effect and lead to some of the electric current entering the head and causing more serious injuries. However, such a possibility should not stop someone carrying a smartphone to use in case of an emergency such as calling for medical assistance.
Someone who is struck by lightning does NOT retain an electric charge, unlike someone in contact with a live electric circuit. Emergency medical help should be summoned as soon as possible. If the person is in cardiopulmonary arrest then cardiopulmonary resuscitation (CPR) should be attempted and continued until paramedics arrive with a defibrillator. Also a public access defibrillator may be available nearby which is safe and simple for a lay person to use. Nearly ten thousand AEDs (Automated External Defibrillators) have been placed in community centres, schools, shopping centres, railways stations, local government offices, gyms and workplaces around the UK. When turned on, most of these computerised life-saving units have spoken prompts, and some may have visual displays to instruct the user. Act to save a life – every second counts. Look for these and similar signs in or on the wall outside buildings:
More details: http://www.communityheartbeat.org.uk/whatisanaed.php
Outdoor risks of being struck, and safety advice
Too often people put themselves at risk by being caught out during a thunderstorm in a wide open and exposed location such as on a hill, mountain, moor, cliff top, beach, lake and sea.
Safe shelter from a lightning strike can be found in a sturdy, well-grounded and enclosed building or a fully-enclosed metal-topped motor vehicle but they may be some distance away when thunderstorms threaten. Thunderstorms are dangerous so have a lightning safety plan. Know where you will go for safety and how much time it will take to get there. Check the weather forecasts in advance of a planned visit to, say, en exposed location such as a hill or mountain and reschedule if there is a risk of a thunderstorm. Avoid being caught out on the wide open spaces of a golf course or sports fields when lightning threatens.
Get to the shore and away from lakes, sea and other bodies of water where you would otherwise be the highest object in the vicinity. Kayaks, jet skis and small boats with no cabins are unsafe locations. Seek shelter onshore inside a well-grounded substantial building or a metal-topped enclosed vehicle. Large boats with cabins, especially those fitted with lightning protection systems, are relatively safe but stay inside the cabin and away from metal surfaces.
Be aware that no place outside is safe when thunderstorms are in the area. If you hear thunder, lightning is close enough to strike you.
Do NOT seek shelter under a tree. Sheltering under a tall tree from the heavy rain of a thunderstorm is dangerous during a thunderstorm. If lightning strikes a tree then the electric current passes down the trunk and may side flash (splash) to the person standing next to it as the human body is a better conducting pathway to the ground.
Do NOT shelter in huts, sheds, park shelters and bus shelters. They are dangerous as these small buildings are often not electrically grounded. Occupants may experience serious, even fatal, electric shocks if lightning strikes them.
Check out the extensive US National Weather Service Lightning safety Website:
and the lightning safety page of the Royal Society for the Prevention of Accidents:
Reminders of when to seek shelter from lightning
There are many rhymes that remind us what to do to keep us safe from lightning such as 'When thunder roars, go indoors'.
The distance of lightning can be estimated using the 'flash-to-bang method'. Light travels faster than sound so we see lightning first before hearing the thunder. Count the number of seconds between seeing the lightning and hearing the thunder and then divide by three to give the distance in kilometres or divide by five to give the distance in miles.
The 30-30 rule has been widely adopted to know when lightning poses a serious threat. People are advised to seek shelter if thunder is heard within 30 seconds of seeing the lightning flash. A time of 30 seconds or less from 'flash-to-bang' indicates that lightning is dangerously close – within 10 km or 6 miles. The other part of the 30-30 rule is to wait 30 minutes from the last lightning flash and thunder before resuming outdoor activities:
'Half an Hour since Thunder roars, now it's safe to go outdoors'
Lightning risk on mountains
One of the most dangerous places to be when lightning threatens is on an exposed mountain, ridge or hill. If thunderstorms are forecast, don't go walking in these places, reschedule your visit. Even if the weather forecast is good it is important to keep a lookout for unexpected bad weather.
If you suspect a thunderstorm is approaching, move downwards rapidly but safely.
If possible choose a route down that does not follow a ridge or other exposed route.
If the storm overtakes you, it is a question of judgement whether you keep moving down to a safer place (metal-topped, enclosed vehicle or well-grounded, substantial building), or stop and make yourself small.
Don't take shelter in cracks, overhangs or small caves: lightning will often follow this route to earth.
Sheltering under a tree is dangerous too.
If you cannot get to a safe location, seek the lowest ground around, away from trees or lakes. Make yourself as small as possible by crouching down or sitting upright with your head tucked down, knees drawn up and hands on your knees. Do not lay flat on the ground as this may increase the electric shock you receive from a ground current if lightning strikes nearby.
Further advice: http://www.mcofs.org.uk/lightning.asp
Indoor risks from lightning
Half of the known incidents in which someone experienced an electric shock from lightning in the UK happened indoors when lightning struck the building they were in. Of the indoor incidents during the past 25 years, around one quarter of people who suffered an electric shock were using a corded (landline) telephone. Others were standing near an external door or window or were near or touching electrical equipment or metal objects connected to the plumbing circuit (radiator, kitchen sink, bath and shower).
If someone experiences an electric shock indoors when lightning strikes the building, usually it has much less serious consequences than electric shocks from lightning outdoors. This is because telephone lines (providing an entry point into a building for electric current from the lightning) and electrical equipment inside the building have surge protection devices to reduce excessive voltages. No deaths inside well-grounded, substantial buildings have been reported in the past 25 years in the UK although they were not uncommon a century ago when buildings lacked electric wiring and plumbing pipes inside the walls and were not well-grounded electrically. Nevertheless, there have been some serious injuries from lightning indoors in the UK in the past 25 years so be cautious and avoid contact with corded telephones and metal objects connected to the electricity and plumbing circuits.
People struck while using a corded (landline) telephone experience an electrical and acoustic shock: they often hear a loud bang or click. They may be thrown across the room and thrown to the ground as their muscles experience a violent reaction to the electrical shock. They may be knocked unconscious briefly and suffer temporary loss of hearing and burns to the face or upper body. Problems to the eyes or ears may continue for months or even years. Most common is for cataracts to form several months or even a year or so later. Using cordless mobile phones, smartphones, computers, laptaps and tablets indoors is generally safe.
Small structures that provide shelter from the rain in gardens, allotments, parks, on mountains and golf courses, or when waiting for a bus are dangerous places to be inside when lightning strikes them. They are not electrically grounded so lightning may not pass around the occupants but may strike them inside through the roof or an open side.
One of worst UK lightning tragedies took place in a park shelter on 21 August 1939 in Valentines Park, Ilford. Twenty eight people had taken shelter there when their picnics were disrupted by a thunderstorm. Five adults and two children were killed and 21 others were injured.
Powerful cloud-to ground lightning over Elderslie, near Paisley, Scotland, on 26 August 2011
© Jeff Blackshaw 2011
More men than women are struck by lightning
Three-quarters (73%) of people struck by lightning outdoors in the UK in the past 25 years were male.
If only fatal incidents are considered, males accounted for four out of five (83%).
This reflects a higher male participation in the activities being undertaken at the time including work (construction, farming) and leisure and sport (hill walking, golf, cricket, football). However, female participation in all these activities has been increasing so we may expect the gender balance of people struck by lightning to reflect this in the future.
TORRO's records for the past 25 years show that Indoor lightning incidents have affected men and women equally.
Largest groups of people struck in the UK?
At Ascot race course, Berkshire, on 14 July 1955, electric shocks were experienced by around 50 people when lightning struck the metal railings opposite the Royal Enclosure. Two people died, one a pregnant woman.
Seventeen boys and adults were injured when a thunderstorm prompted the group to take shelter from the rain under a tree at a football match for under-10-year-olds around midday at Aylesford, Kent, on 2 September 1995. Lightning struck the tree and side flashed to a large golfing umbrella that one man was holding. Fifteen were treated for minor burns, damage to their eyes and shock, with five detained in hospital. Four had to be resuscitated. Three had serious burns.
During the night of 1 September 1994, 14 teenagers sleeping in tents in a back garden in Tunbridge Wells, Kent, suffered electric shocks when lightning struck the largest tent. Eight were treated for burns and/or shock, with three being detained overnight.
Incidents with more than one fatality in the UK?
In the past 25 years, when there have been a total of around 50 fatalities in the UK. Although more than one person has been killed on the same day in separate incidents, as happened on the Brecon Beacons in south Wales on 5 July 2015:
Only one incident during the past 25 years is known to have resulted in more than a single fatality. This took place on 22 September 1999 at Hyde Park, London, when two women were struck and killed while sheltering beneath a tall maple tree:
Worst years for lightning fatalities in the UK?
During the past 50 years, the years with the highest number of lightning fatalities were 1970 with 12 deaths and 1982 with15 deaths.
In comparison, some years in the nineteenth century resulted in a much higher number of fatalities.
Official statistics are available only for England and Wales in the earlier years but they reveal the worst years as 1852 (45 deaths), 1872 (46 deaths) and 1895 (43 deaths). This was a period when the national population was around one-third of today's population.
Fewer lightning fatalities since the mid-19th century
The average annual number of lightning fatalities in each decade for the past century and a half for England and Wales were:
1850s = 21
1860s = 13
1870s = 23
1880s = 18
1890s = 21
1900s = 13
1910s = 18
1920s = 9
1930s = 12
1940s = 10
1950s = 10
1960s = 4
1970s = 4
1980s = 4
1990s = 3
2000s = 1
The number of fatalities refer only to England and Wales as national statistics for Scotland did not begin until 1951 and Northern Ireland until 1964. Annual fatalities in Scotland and Northern Ireland were typically none, one or two a year. By far the most UK fatalities have occurred in the more thunderstorm-prone England during the past century and a half.
Refer to the article by Derek Elsom (2015) for fuller details:
or contact the author at email@example.com
Reasons for a large decrease in the annual number of lightning fatalities since the 1850s
- Reduction in the number of people employed in outdoor occupations, especially agriculture;
- Many nineteenth century buildings lacked electrical and plumbing circuits which would otherwise have provided a route to earth for the lightning's electric current in the walls and away from the occupants;
- Movement of people from the countryside to urban areas where more people worked at indoor occupations where the buildings provided relative safety;
- More buildings were required by regulations to install lightning protection (lightning conductors, electrical surge protectors);
- Strengthening of health and safety regulations for outdoor workers – requirement to stop work if thunderstorms approaching. Farm tractors had to have cabins fitted since the 1970s. These act as a Faraday Cage and keep the electric current from the lightning away from the driver before it discharges to the ground);
- Improved technical and operational safety of aircraft including commercial aircraft, helicopters and gliders;
- Lightning warning systems (klaxons) on golf courses;
- Improved medical attention for lightning casualties, including more people knowing how to administer cardiopulmonary resuscitation (CPR), paramedics and ambulances reaching casualties more quickly and being better equipped to give emergency treatment (carrying defibrillators), greater availability of community AEDs (automated external defibrillators), and using helicopters to transfer casualties quickly to hospital from remote locations such as mountains;
- Increased awareness of the danger posed by lightning as a result of school and public education, and for people to take the necessary actions to reduce personal exposure to the lightning risk;
- Individuals and organisations (e.g. sports clubs) responsible for their members are today more disposed to reschedule or discontinue their activities when thunderstorms are forecast or develop in their area;
- Public confidence in thunderstorm forecasts has improved as their accuracy has increased and such forecasts have become more readily available e.g. smartphone apps which alert the user to the lightning risk and advise 'seek shelter now'.
Routes by which someone is struck by lightning
Not everyone struck by lightning experiences a direct strike.
There are many routes and mechanisms by which someone may be struck.
A direct strike may account for a relatively small proportion of injuries and fatalities as shown below (the percentages may vary from study to study):
Source: Environment Canada
Electric shocks from lightning can occur when someone is outdoors and in contact with an object that is struck by lightning such as a metal gate, fence, tree, umbrella, golf club, fishing rod or even another person, or indoors touching an object that is part of the conducting route (electrical and plumbing circuits) for the lightning discharge to reach the ground when it strikes the building.
When an object is struck by lightning, the electric current may side flash or splash from the object to a person nearby as the human body is a better conducting route to earth than the object initially struck.
Side flashes commonly involve a tall tree. A 20 to 30 metre tree is a strong contender to provide the initial attachment to the downward stepped leader of a lightning strike in a relatively open location such as a park, golf course or farmland if lightning was going to strike in the general vicinity. Lightning will flow down the tree and jump to the person standing nearby.
In contrast, holding an umbrella, golf club or fishing rod in an open location offers a much smaller attachment radius for the stepped leader than a tall tree.
Only if lightning was about to strike anyway within, say, 2 to 3 metres of the person holding such an object would the object be the preferential attachment point rather than the point on the ground the downward leader was heading for.
When lightning strikes an object or the ground, the electrical current spreads outward from the strike point rather like ripples spreading out from a pebble dropped in a pond. Someone standing across these ripples experiences an electrical current up one leg and down the other as the human body offers less resistance for the current to pass than the ground. This is called the step voltage effect or ground current.
Leg muscles spasm violently and a person is thrown off their feet. Victims may not be able to stand as they continue to experience numbness or paralysis in their legs for minutes or even hours later. Entire sports teams have been knocked over by the step voltage effect. The wider apart the feet, the greater the induced electrical current passing through the body which explains why sheep, cows and horses are often killed by this effect.
Also if within around 20 metres of a lightning strike, instead of the ground current spreading out relatively uniformly from a strike point as a ground current, the electric current may take the form of ground surface arcing, when the lightning flashes along the ground surface in the form of a star burst of flashes. Ground surface arcs carry more current than the areas in between so if a person experiences one of these bursts then the effects may be much more serious.
Unconnected upward leaders or streamers.
Overlying thunderstorms attract upward streamers from objects at the ground, one or more of which may connect with the downward stepped leader to create a cloud-to-ground lightning flash. Many upward streamers fail to make contact but the electric current of an upward streamer originating from a person may be intense enough to cause them injuries. Signs of an upward streamer include a person's hair standing on end and for metal objects being worn or carried and nearby rocks to buzz or crackle.
The shock or pressure wave from a nearby lightning strike may give rise to blunt trauma injuries.
Some of the ways of being struck by lightning are illustrated at:
Non-electrical ways of being injured by lightning
Lightning may cause injuries through various non-electrical effects:
- sudden explosive expansion of the air around the lightning channel. The pressure or shock wave may throw a person violently to the ground causing injuries;
- intense magnetic fields generated around the channel by the very high electrical currents present. These may induce large but short-lived electric currents in a body causing the heart to stop or to go into rapid ventricular fibrillation causing death with no marks on a body. Researchers have suggested that healthy young climbers and hikers found dead with no visible evidence of being struck by lightning may have been killed by this effect.
Indirect effects of lightning include:
- injuries through being struck by falling roof tiles and masonry when lightning damages a building;
- fires initiated by lightning discharges due to overheating of electrical circuits and appliances in buildings. This may result in the occupants suffering burns and the effects of smoke inhalation;
- lightning striking near a motor vehicle, especially at night, may temporarily blind the driver causing them to lose control of the vehicle and crash;
- farm animals stampeding if frightened by thunder and lightning and resulting in the trampling of people nearby. A rider may be thrown if their horse is startled;
- Lightning hitting a tree may instantly vapourise sap, causing strips of bark and branches to be ejected explosively. These may strike people nearby, causing injury or even death.
Lightning books: further reading
In Lightning: Nature and Culture (Reaktion Books, London, 2015) Professor Derek M. Elsom explores the subject of lightning in relation to its characteristics and different forms, improvements in scientific understanding, its impacts, ways to reduce the risks it poses to people and activities, and how lightning is embedded in our culture from myths, folklore and legends to art and design:
University of Chicago Press
Other key books about lightning, lightning injuries and lightning safety include:
Andrews, Christopher, Mary Ann Cooper, Mat Darveniza and David Mackerras, Lightning Injuries: Electrical, Medical and Legal Aspects (Boca Raton, 1992)
Bouquegneau, Christian and Vladimir Rakov, How Dangerous is Lightning? (New York, 2010)
Rakov, Vladimir A. and Martin A. Uman, Lightning: Physics and Effects (New York, 2003)
Smith, Craig B., Lightning: Fire from the Sky (Newport Beach, 2008)
Uman, Martin A., All About Lightning (New York, 1986). This edition is an unabridged and corrected publication of Martin Uman's Understanding Lightning (Pennsylvania, 1971)
Uman, Martin A., The Art and Science of Lightning Protection. (Cambridge and New York, 2008)
Lightning near Roche, Cornwall, 17th July 2014 (© Matthew Clark)