How long does a thunderstorm last?
A thunderstorm consists of 1 or more "cells"...each usually
lasting 20-30 minutes. The entire lifetime of a thunderstorm can
vary. Typical afternoon thunderstorms in the summer usually consist
of just 1 cell, thus lasts 20-30 minutes. Severe thunderstorms can
consist of numerous cells, and last several hours. Hope this helps.
For more information about thunderstorms and other weather hazards,
I've put together a public training course, which can be found at
http://www.storm-prep.com . There's also some interesting weather
trivia at that site.