Lightning and thunder
When you see lightning, you can count to estimate how far away it strikes.
The risk of being struck by lightning is small, but direct lightning strikes can cause serious injury or be fatal. If you count the seconds between a lightning flash and a thunderclap, you may judge how far away the lightning struck. Three seconds between lightning and thunder means that lightning has struck one kilometre away. The risk is most likely gone 30 minutes after the last lightning strike.
What to do when there is lightning:
- Stay indoors.
- Avoid being in open fields.
- Unplug power cords from wall outlets.
- Avoid standing under trees or other tall objects.
- Avoid being in and on water.
Checklist - safe places
Although there is no single location that provides complete protection, it is useful to know the following:
- It is generally safer inside buildings, the bigger the better.
- Avoid touching or standing near lights or other electrical products, water systems (taps and showers) or fireplaces (in case of a lightning strike in the chimney).
- Close all windows and doors (to avoid broken glass and prevent the possible spread of fire).
- Avoid going out onto balconies or verandas, for example.
- Cars and other enclosed metal vehicles are generally safe, but:
- Large windows and other large non-metal surfaces reduce safety.
- Don't touch metal parts or the radio when you are in the car.
- Tyres have no protective effect.
- A lightning strike can damage the car's electronics and tyres.
- Staying in tents, open boats and sailboats (if not properly protected) or on bicycles and motorbikes can also be dangerous.
- An umbrella, golf club, metre stick or flying kite on a string can act as a lightning rod and should be avoided during thunderstorms.
This is based on information from The Swedish Civil Contingencies Agency ("MSB"), the Swedish weather agency SMHI, and The Swedish Electrical Safety Authority Elsäkerhetsverket.