A Warm Start to January

2020 has gotten off to a warmer than average start in the Nation’s Capital.  Similarly, last month ended with nine consecutive warmer than average days, that helped it finish 2.4° warmer than average.  In fact, eight of the last nine Decembers have now been warmer than average in Washington, D.C.

January 2020 has felt more like early-March so far with highs yesterday and today in the mid to upper 50s across the DC Metro Area.  A cold front will, however, help usher in cooler and more seasonal temperatures to conclude the weekend.  Average high and low temperatures in the Nation’s Capital during the month of January are 44°/29° on both January 1 and January 31.  However, DC’s coldest average high/low temperatures are 43°/28° and occur from January 12 – 22 according to the National Weather Service.  Eleven of the last 20 January’s have been colder than average in the Nation’s Capital, since January 2000.  

DC’s warmest January temperature on record was 79° on January 26, 1950.  DC’s coldest observed January temperature was -14° on January 1, 1881.  Weather records in the Nation’s Capital date back to 1871.  Weather observations were made downtown prior to the 1940s when National Airport opened.  Keeping weather observations at any site along a body of water influences temperature readings.  The DC Metro Area has also become significantly more developed in recent decades that’s enhanced the urban heat island effect.  These two things have significantly contributed to making DC warmer in recent years compared to earlier decades.

January is DC’s coldest month on average, but February is its snowiest by a small margin (5.6” vs. 5.7”).  Several of DC’s largest snowstorms occurred in January including DC’s largest, “The Knickerbocker Storm” of 1922, and the blizzards of 1996 and 2016.  It’s also worth noting that while measurable January snowfall occurred in 19 of the last 20 years in the Nation’s Capital, only eight of those January’s have had above average snowfall.  

November and December 2019 were both considerably warmer than average and this month has continued that trend.  Unfortunately for winter weather enthusiasts, NOAA’s Climate Prediction Center expects above average temperatures to continue in the Mid-Atlantic Region at least through the middle of January.  However, the right ingredients have to come together only once, though, to produce a significant winter storm.