Thunderstorms can occur any day of the year and at any time of the day, but are most common in the late afternoon and evening during the summer months. Thunderstorms are generally beneficial. They provide needed rain for crops, plants, and reservoirs. However, about five percent of thunderstorms become severe and can produce tornadoes, large hail, damaging downburst winds, and heavy rains causing flash floods. Thunderstorm can develop in less than 30 minutes, allowing little time for warning.
All thunderstorms produce lightning which can be deadly.
The National Weather Service does not issue warnings for ordinary thunderstorms nor for lightning. The National Weather Service does highlight the potential for thunderstorms in the daily forecasts and statements. Be alert to the signs of changing weather, such as darking skies, a sudden windshift and drop in temperature, and having a warning device such as NOAA Weather Radio. Staying alert and listening to NOAA Weather Radio can mean the difference between life and death when a thunderstorm approaches. Lightning Flash Density Map computed for 1989 by the Electric Power Institute, courtesy of the University of Virginia, Climate Division.