Tornadoes And Outbreaks Can Happen In Fall And Winter, As Recent History Shows

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 might sound 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 2023.

There is a pronounced peak in spring and early summer. But, while fewer than spring, tornado counts remain rather steady in fall and winter. All of the months in those seasons average at least 42 tornadoes.

Just like spring, fall is a battleground season: 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.

Larger outbreaks occur when warm, humid air from the Gulf of Mexico meets up with the increasingly stronger cold fronts and jet stream winds that typically sweep across the country. That's generally the same setup we often see in spring.

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

October's tornado risk can still extend into the north: While it doesn't happen every year, the possibility of tornadoes can reach into the upper Midwest and Northeast during fall's first full month.

Recent October outbreaks include an Oct. 20-21, 2019, outbreak in six southern states, involving 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 greatest tornado risk is the Deep South: Parts of the South, especially the lower-Mississippi valley, have the greatest risk. But, the possibility of tornadoes can extend farther north into the mid-Mississippi Valley, lower Ohio Valley and mid-Atlantic states.

November 2022 was a reminder with an above average 68 tornadoes in the month, most of which were in the South. Deadly tornadoes struck Texas and Oklahoma on Nov. 4, and then Alabama early on Nov. 30.

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.

Wintertime tornadoes are a concern too, especially in the South: Arctic cold fronts usually 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.

T​he December 9, 2023 outbreak in the Tennessee Valley claimed seven lives as destructive tornadoes tore through the north Nashville metro area and near Clarksville, Tennessee.

D​ecember 2021 is the most recent extreme example, and not just for the South. T​wo severe weather outbreaks tore through parts of both the South and Midwest in a span of five days.

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: January 2023 had 130 confirmed tornadoes, making it the third most twisters the month has seen in records dating back to 1950. Tornadoes killed seven people in Alabama and one person in Georgia during a Jan. 12 tornado outbreak that hit the South.

February has had a streak of deadly tornadoes in recent years, as well as notable outbreaks such as Super Tuesday 2008 and Leap Day 2012.

Fall, winter tornadoes are often a danger after dark: 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, 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?

-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 for your area.

-Your smartphone can alert you. Most 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 the "do not disturb" feature is set to off overnight. 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 ready to go for where you will seek shelter if a warning is issued.