When you observe lightning, stop your outdoor activity and seek safe shelter. Lightning can travel much farther than you can see. If you see lightning, any lightning, you are in danger even if the flash appears to be at a considerable distance from you.
When you hear thunder, immediately stop your outdoor activity and seek shelter. The sound of thunder dissipates rapidly in the atmosphere. Lightning can be dangerously close, yet the sound of its thunder may cause you to conclude that it is at a considerable distance. When you hear thunder, you are in immediate danger.
When to resume activities:
Remain in your safe location for 30 minutes after the last sight of lightning or the last sound of thunder.