In central PA, severe weather can happen anytime throughout the year. However, there is a climatological peak when it comes to our worst severe weather days. I looked back to find the number of days with five or more severe weather reports in our viewing area since 2000. Keep in mind, this combines reports of hail, damaging wind, and tornadoes. It’s no surprise that June or July are our most active months, with 34 and 33 days of five or more severe weather reports, respectively. Severe weather frequency diminishes significantly by September and October, with only two 5+ severe weather report days occurring between November and January since 2000. So, while severe weather has certainly happened during the fall and winter, when it does happen, it tends to be much more isolated.

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In the entire state of Pennsylvania, tornadoes specifically are also most common in the months of June and July. However, by looking at the orange and red-colored bars (which represent strong tornadoes), you’ll note that EF3+ intensity tornadoes are most common during the months of May and June. This is mainly because higher amounts of wind shear (changing of wind with height) are present in the lower atmosphere during the late spring when compared to summer. Two examples of tornado outbreaks during this time are May 31, 1985, and June 2, 1998. This year featured a well below average year when it comes to tornadoes, with zero tornadoes confirmed in our viewing area as of early December.

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