Virginia averages 35 to 45 thunderstorm days a year. Thunderstorms can occur any day of the year and at anytime of the day, but are most common in the late afternoon and evenings during the summer months.

About 5% of thunderstorms become severe and are capable of producing tornadoes, large hail, damaging winds, and heavy rains causing flash flooding. Severe thunderstorms can develop in less than 30 minutes, allowing little time for warning. To alert the public about possible severe thunderstorms, the National Weather Service issues watches and warnings.

Thunderstorm Watch vs. Warning

• A severe thunderstorm watch means that the conditions are favorable for the development of severe thunderstorms. If a watch is broadcast, stay tuned for further information and possible warnings and be prepared to take cover.
• A severe thunderstorm warning means conditions are occurring or imminent. Warnings are issued for individual counties and include the severe thunderstorm’s location, direction, and speed. If you are in the path of the severe thunderstorm, seek shelter immediately.

Severe Thunderstorm Characteristics

• Winds greater than 58 miles per hour.
• Hail greater than three-quarters of an inch.
• Lightning can travel horizontally up to 10 miles in any direction, which means that a thunderstorm may not to be directly overhead, nor does it need to be raining to produce lightning in an area.