When should activities be stopped during storms?

• If you see lightning. The ability to see lightning varies depending on the time of day, weather conditions, and obstructions such as trees, mountains, etc. In clear air, and especially at night, lightning can be seen from storms more than 10 miles away if obstructions do not limit the view of the thunderstorm.
• If you hear thunder. Thunder can usually be heard for a distance of about 10 miles if there is no background noise. Traffic, wind, and precipitation may limit the ability to hear thunder to less than 10 miles. If you hear thunder, though, it is a safe bet that the storm is within ten miles.
• If the skies look threatening. Thunderstorms can develop directly overhead and some storms may develop lightning just as they move into an area.