Connecticut’s Tornado Season

I decided to take a look back and see where the average “tornado season” falls for this area.
Where frequency is the running 10-day daily frequency of a tornado between 1950-2013

The months with the most tornadoes in Connecticut have been June and July. Although August has seen a fair amount too, the season is on a decline by that point. The data considered is from 1950-2013.

The rough mid-point of the tornado season in Connecticut is July 12th. This means that the threat of tornadoes begins to decline beyond mid-July. This makes sense, because the hottest time of the year in Connecticut is the first half of July and temperatures begin to decline as the summer goes on. Also, the length of daylight gets shorter later in the summer…since thunderstorms and tornadoes rely heavily upon daytime heating to destabilize the atmosphere, it is expected that thunderstorms and tornadoes become less common later in the year.

I came up with a trend-line above, which smooths out the data. The data largely resembles a bell curve, except the data levels off in October. Although tornadoes are less likely in the fall, they have happened in the past. Perhaps the most famous example is the October 3rd, 1979 tornado that hit Windsor Locks. Not only was that a late-season tornado, but it was one of only two F-4 tornadoes to strike Connecticut since 1950. Now, since the sampling of tornadoes above is rather small, with only 91 tornadoes considered, any gaps in the data (for example, only four tornadoes in October) will skew some of the results.

Source data for the tornado reports from 1950-2012: Tornado Project
Information for 2013 tornadoes was retrieved from the Storm Prediction Center