In order to avoid finding yourself in great danger and especially if you are an athlete, mountaineer, fisherman, farmer, etc. or you are otherwise often outdoors, do please find out the weather conditions beforehand.This is particularly important if you will be in an area where it could be difficult to find protection in case of a thunderstorm. Never underestimate the weather or indeed any other natural phenomenon.
As soon as you can see lightning in the sky, you must immediately seek a safe place to protect yourself. Even when you can only hear thunder, you are already in danger if you have not taken appropriate precautions.
If the interval between lightnings is 30”, then the thunderstorm is within 10 km away from you and you are in imminent danger of being struck by lightning.