Lightning lights up the sky at Barksdale Air Force Base, La., June 5, 2018. During lightning storms, personnel are reminded to stay sheltered in buildings, underground shelters or automobiles. (U.S. Air Force photo by Airman 1st Class Tessa B. Corrick)

Wisconsin’s Monroe County averages 39 thunderstorm days per year.

It is important to know what a severe thunderstorm is and the actions to take if a severe thunderstorm is approaching.

A thunderstorm is defined as severe if it produces damaging wind gusts (58 mph or higher), large hail (one inch or larger in diameter), a tornado, or a combination of these elements. Thunderstorms also produce deadly lightning and heavy rains.

Most thunderstorms do not become severe. Severe thunderstorms can occur at any time of the year, day or night. The peak time for thunderstorms is April through September during the afternoon or evening hours.

The most common type of severe weather is damaging thunderstorm winds, also known as “straight line winds.” Strong thunderstorm wind gusts can reach hurricane force and, in extreme cases, more than 100 mph. Wind damage can be extensive and affect entire counties.

Objects like branches, trees, barns, outbuildings, high-profile vehicles, and power lines/poles can be toppled or destroyed. Wind gusts can also cause damage to roofs, windows, or homes.

Large hail is also common and can produce property damage. Usually, large hail does not become life-threatening unless people are stuck outdoors without shelter. Hail is considered severe when it reaches the size of a quarter or larger.

People can take precautions to help protect themselves and their property from damaging storms.

Keep trees trimmed near houses and other buildings. Put away or secure loose objects in yards and on decks.

Conduct emergency drills with family members so that everyone knows what to do in case of a storm. Take first aid and CPR training to be prepared for medical emergencies.

It’s important to have a reliable source of weather information, whether it’s a local news station, a mobile app, or a weather radio.

When a severe thunderstorm moves into the area, take action to protect both family and property.

When a warning is issued, move to a sturdy building. Stay away from windows. If boating or fishing, move to shore.

Try to get to a secure shelter if in a motor vehicle; it can be very dangerous to drive through thunderstorms.

For more information on severe weather hazards, visit:

• www.weather.gov/safety/thunderstorm.

• www.nssl.noaa.gov/education/svwx-101/thunderstorms/.

• www.ready.gov/severe-weather.