The ‘30-30 Rule’ offers the best thunder and lightning safety guidance and provides a good way of ensuring everyone is sheltering during the most risky parts of the storm.

Breakdown:

"30 seconds": When you see lightning, start counting the seconds until you hear thunder. If the count is 30 seconds or less, the storm is close enough to be dangerous, and you should seek shelter. When the lightning strike is 6 miles away, everyone needs to leave the pitch
"30 minutes": After the last thunder and lightning event, wait at least 30 minutes before resuming training or play.
The “30 minute” clock starts again for each new thunder and lightning event

Important Notes:

Seek shelter inside the clubhouse or a car keeping away from, and getting out of wide, open spaces, do not shelter beneath tall or isolated trees.
The inside of a car is a safe place to be in a storm, lightning will spread over the metal of the vehicle before earthing to the ground through the tyres.
Even if you don't see the lightning, just hearing the thunder is enough reason to seek shelter, this is a good back up rule.
Research shows that people struck by lightning are predominantly hit before and after the peak of the storm.
Lightning can strike as far as 10 miles from the area where it's raining, meaning it can be dangerous even if it's not raining at the pitches.
Distance calculation - count the seconds between seeing the lightning and hearing the thunder. Divide the number of seconds by 5, eg 30 seconds/5 = 6 miles

By following the 30/30 rule and other lightning safety guidelines, you can significantly reduce the risk of being injured or killed by a lightning strike.