October 2021: A Mild One in the Northeast

Leaves taking too long to change? Where’s the cooler weather? These are likely the questions that were asked during October 2021 as the transition to autumn was slow to begin. With the exception of Mount Washington, no meaningful snow fell or true frost ever occurred in the Northeast as virtually the whole month featured above normal temperatures, occasionally by 10 to 15 degrees! Rainfall, on the other hand was near normal, as two large systems (including a nor’easter) brought plentiful rain during the last week of the month.

Quiet weather began October thanks to a large high pressure dominating the eastern US. A brief disturbance on the 5th brought some rainfall, and while most of it was run of the mill, a few spots like Philadelphia saw 2”+ of rain. Following that, the Northeast and Mid-Atlantic embarked on the warmest stretch of the month through the middle of October as high pressure once again anchored itself overhead. Temperatures soared into the 70s and 80s, particularly across the Mid-Atlantic. A cold front on the 16th then interrupted this pattern for only a day, before temperatures rebounded by the third week.

While the remainder of the month stayed slightly cooler, it averaged above normal across all the major cities. In typical climatological fashion, highs took a step down into the 50s and 60s (70s in Maryland and Virginia), while the overnights cooled off into the 40s. The 25th saw a brief stint of severe weather, with damaging wind gusts between Washington, D.C. to places west of Philadelphia, PA. Indeed, the most active stretch came during the last week of the month, as a robust nor’easter dropped a widespread 2 – 5” of rain between the 26th and 27th. Winds also gusted upwards of 50 – 60 mph along coastal regions, especially in Massachusetts. Right on the heels of that was yet another complex disturbance which didn’t bring as much precipitation on the 29th, yet still added to the monthly total. This system lingered across New England into the 30th before departing, giving the Northeast a seasonable and dry Halloween for the trick-or-treaters.

Overall, all major cities recorded a top 5 warmest October or better. October 2021 was warmest on record for two cities, as Scranton, PA averaged nearly 60 degrees and Baltimore, MD finished out at 65 degrees. In terms of precipitation, despite some longer dry periods, the two disturbances near the end of the month helped bring most places to around normal, between 3.50” and 5.00”.