If you are inside and the skies get very dark and the rain is coming down hard, bring the children to the window to look for lightning. You can explain that lightning is a loud noise caused by electricity in the clouds. Once the children see the lightning, have them count slowly until they hear the thunder. It takes about 5 seconds for the sound of thunder to travel one mile so the higher the number the farther away the storm is. Repeat this each time you see lightning. They can then figure out if the storm is coming closer or if it is moving away.
This is a great way for the children to think about storms, to work through their fears about the loud noises thunder makes, and to use their counting skills for something that connects to their lives.