A thundershower is a short rainstorm accompanied by thunder and lightning. Unlike a gentle drizzle that lasts all day, a thundershower arrives suddenly, pours down heavy rain for anywhere from a few minutes to an hour or so, then moves on. You might be playing outside on a summer afternoon when dark clouds roll in, thunder rumbles, lightning flashes, and rain dumps down in thick sheets. Then, almost as quickly as it started, the storm passes, the sun comes back out, and you see steam rising from the warm pavement.

Thundershowers form when warm, moist air rises quickly into cooler air above, creating towering clouds called cumulonimbus clouds. The rapid movement of air inside these clouds generates the electrical charges that become lightning, and the sudden expansion of air from the lightning's heat creates the boom of thunder. That's why thundershowers are common on hot summer days: the heat provides the energy that builds these powerful but brief storms.