Tornadoes And Severe Thunderstorms Aren't Just For Spring And Summer

T​ornadoes and severe thunderstorms are most common in the United States in spring and summer, but they can also happen in fall and winter, whenever the right conditions are in place.

That statement might be surprising. Fall usually conjures up visions of the first cold fronts of the season sweeping away summer's heat and humidity. Crisp, cool fall mornings don't seem to mesh with thoughts of severe thunderstorms.

A​nd let's face it, winter's cold and snow seems the polar opposite - pun intended - from tornadoes.

The data tells a different story.

B​elow is a graph of average monthly tornadoes in the U.S. over the most recent 20 years through 2021.

Y​es, there's a pronounced peak in spring and early summer. But, while fewer than spring, tornado counts remain rather steady in fall and winter.

F​all's Risk

These tornado counts don't plunge to zero after summer because the conditions that spawn them can still occur in fall and winter in some parts of the country.

Just like spring, fall is a battleground season, when surges of warm, humid air from the Gulf of Mexico sometimes meet up with the increasingly stronger cold fronts and jet stream winds that typically sweep across the country.

When this mix of ingredients comes together, it can ignite numerous severe thunderstorms that produce damaging winds, large hail and tornadoes.

I​n October, this risk of tornadoes can still stretch as far north as the upper Midwest and Northeast.

A​mong recent October outbreaks was an Oct. 20-21, 2019, outbreak in six southern states, including an EF3 on the north side of Dallas; Pennsylvania's largest October outbreak in 2018 and an early October 2013 outbreak that spawned an EF4 tornado in Wayne, Nebraska.

N​ovember's tornado risk is highest in the lower Mississippi Valley and South, but can also extend into the mid-Mississippi Valley, lower Ohio Valley and mid-Atlantic states.

O​ne of the nation's worst tornado outbreaks happened just days before Thanksgiving 1992 when a swarm of 105 tornadoes tore through parts of 13 states from Texas to the Carolinas. The severe weather claimed 26 lives and injured another 638.

Winter, Too

As you would expect, Arctic cold fronts often surge through the South in winter, cutting off any chance of thunderstorms – much less severe thunderstorms – in the Lower 48.

But when that cold air doesn't penetrate into parts of the South in winter, an active jet stream overlapping warmer and more humid air can ignite severe thunderstorms ahead of an advancing cold front.

D​ecember 2021 was the most recent example, and not just for the South. T​wo severe weather outbreaks tore through parts of the South and Midwest in just five days in mid-December 2021.

The first outbreak of 66 tornadoes included the long-track Mayfield, Kentucky, EF4 tornado. That was followed by an unusual December derecho in the Plains and upper Midwest that spawned another 99 tornadoes.

I​t's not just December, either. A​ January 21-23, 2017, outbreak spawned an EF3 tornado in Albany, Georgia, that traveled at least 70 miles.

February has had a streak of deadly tornadoes for the past several years, as well as notable outbreaks such as Super Tuesday 2008 and Leap Day 2012.

D​on't Forget Severe Weather Safety

A​nother important aspect to fall and winter severe weather is the tendency for more tornadoes to occur at night, given fewer hours of daylight in standard time, rather than daylight time.

This is important since tornadoes occurring at night are more than twice as likely to be deadly as those during the day, according to a recent study.

How can you be warned if you're sound asleep? Here are some tips:

-Buy a NOAA weather radio. You can find these at most electronics retailers. Warning alarms can be set to sound when any National Weather Service tornado or severe thunderstorm watch or warning is issued.

-Your smartphone can alert you. Most newer smartphones are capable of receiving wireless emergency alerts from your local NWS office. These include tornado warnings. Make sure your smartphone is charged sufficiently and left on overnight, and a special tone and vibration will occur twice when a tornado warning is issued. Note, however, this will not sound for a tornado watch or severe thunderstorm warning.

-Other weather apps can also alert you. Many weather apps, including The Weather Channel app, can send alerts to your smartphone, tablet or smartwatch.

-Know where to go. Have a plan in place in advance for where you will seek shelter.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.