Tornadoes in the D.C. region, defined as places within 100 miles of the city in this graphic. (Ian Livingston/The Washington Post)

About 20 minutes before 2 p.m. Monday, a quick-hitting but destructive tornado took a swipe at Salisbury, Md. Rated EF1 on a scale of 0 to 5, it was powerful enough to toss cars like toys, yet docile in leaving behind no injuries.

The twister came on the heels of a more powerful one at the end of July on the east side of the Chesapeake Bay. And, before that, a small swarm of tornadoes targeted the immediate D.C. area in April.

It turns out all of this tornado activity isn’t some sort of freak anomaly, but rather par for the course for our region.

While the D.C. area very seldom witnesses violent tornadoes, rated EF3 or higher, the kind much more common in the Midwest — it is served a healthy diet of smaller storms. Data show that what the area lacks in tornado intensity, it makes up for in quantity and regularity.


Tornadoes by month in the region. In this graph a buffer of 100 miles was placed on D.C. and Salisbury to gather tornadoes in the local regions. Salisbury, of course, has much more water in that sample, hence the lower numbers. (Ian Livingston/The Washington Post)

The regions surrounding Washington and Salisbury both average around 20 to 30 tornadoes per year, with a typical peak during the summer when thunderstorms are most prevalent.

In the D.C. area, the most twisters typically occur in June and July, while August is the peak month in Salisbury.

While the annual average number of August tornadoes around D.C. is about three, they have occurred in just about 70 percent of Augusts (17 of the past 25), signifying they tend to come in bunches.

Tallying up all of the tornadoes so far in 2017, the total numbers are pretty close to average in the broader D.C. area


Tornadoes in the D.C. region in 2017, compared to average. (Ian Livingston/The Washington Post)

April was super active, thanks to a single day. Those tornadoes were almost all short-lived and weak — seven of eight were rated EF0. Still, it was a top-end tornado day in these parts. Two tornadoes impacted the District itself that day — an occurrence unprecedented in the modern record.

We must, however, be cautious not to look at too small of an area for records that amount to little more than bar trivia. Take away the April event, and it’s been a quiet year — notwithstanding the late July EF2 tornado on the east side of the bay.

It may be somewhat surprising, but the D.C. area is among the regions of the United States that most commonly experiences tornadoes year in and year out. In a gridded analysis focused on the 10 years ending 2016 (see below), it was one of a few across the country that had a tornado every year. Note, however, this may be in part due to the region’s population density and the resulting number of potential eyewitnesses and several radars that help detect storms.


The 50-by-50-mile boxes had at least one tornado every year from 2007-2016. (Ian Livingston)

Our region also stands out on a map showing the frequency of experiencing a tornado at the county level in a given year.


Tornado frequency by county, on an annual basis, using a 1992-2016 averaging period. (Ian Livingston/The Washington Post)

In the 25 years ending last year, each D.C. region county has seen tornadoes in 30 to 60 percent of the years. The counties on the Maryland side of the Potomac all saw tornadoes about every other year. Such frequencies rank right up there with many counties in tornado alley.