Looking Ahead to Winter

 

Despite yesterday with a high of only 57°, October 2020 is well-positioned to finish as a warmer than average month.  Average monthly temperatures (combining daily high and low temperatures) in the Nation’s Capital were 3° warmer than average through October 24.  By comparison, yesterday’s weather felt especially cold following a five-day stretch temperatures that were at least 10° warmer than average.

Average high temperatures during the month of October range from 74° at the start of the month to 64° on Halloween.  Meanwhile, temperatures during the day yesterday remained in the mid to upper 40s with light rain and drizzle that made it feel more like a late November day.  However, that shouldn’t prevent this month from finishing well above average.  There is also the prospect of heavier rain later in the week in the DC Metro Area with the remnants of Tropical Storm Zeta. 

Some may wonder if a warmer than average October combined with La Nina conditions is a reliable indicator of what the upcoming winter season will be like.  The short answer is no, but there are some exceptions.  For example, October 2017 was DC’s third warmest on record and the 2017-2018 winter season had a weak episode of La Nina.  La Nina winters are often warmer than average, with near average precipitation in the Nation’s Capital.  The 2017-2018 winter season as a whole (December 1 – February 28) was 1.9° milder than average.  Only 7.8” of snow occurred – or approximately half of DC’s seasonal average of 15.4”.

Conversely, DC’s warmest October occurred in 2007 and the 2007-2008 winter featured a strong episode of La Nina.  Consequently, the Nation’s Capital had less than a third of the seasonal average with only 4.9” of snow.  That winter was also 2.7° warmer than average.

NOAA’s Climate Prediction Center says there’s an 85% chance La Nina conditions will continue through the 2020-2021 winter season.  That doesn’t bode well for winter weather enthusiasts in the DC Metro Area.  However, they shouldn’t give up hope for snow this winter – certainly more than the 0.6” that occurred all of last winter.  Even in a warmer than average winter, the right ingredients only need to come together once to produce a significant snow event in the Nation’s Capital.