Although conditions must be very specific for a thunderstorm to develop, thunderstorms remain the most common kind of extreme weather. Before a thunderstorm can develop, there have to be three conditions present: the air has to be full of moisture, there must be either an intensely heated portion of Earth’s surface sending warm air up quickly or an approaching cold front, and the warm air that is rising must be warm enough to stay warmer than the air it passes through as it rises. The moisture in the rising air condenses, clouds form and a storm begins.