We follow the 30-30 rule.
The ‘30-30 rule’ offers the best lightning safety guidance for the general public. When you see lightning, count the time until you hear thunder. If that is 30 seconds or less, the thunderstorm is close enough to be dangerous.
Individuals who feel their hair stand on end or skin tingle or hear crackling noises, should assume the lightning-safe position (crouch on the ground, weight on the balls of your feet, feet close together, head down, ears covered). Wait 30 minutes or more after the lightning flash before leaving shelter and resuming the activity.
During a lightning storm Do Not: Use the telephone or hand held radios – including cell phones