DC’s Warm Start to January

The first half of January 2020 has been exceptionally warm in the Nation’s Capital.  Only January 9 was slightly colder than the daily average (43°/29°) with high/low temperatures of 41°/29°.  A few warmer than average days loom for Washingtonians before a major shift in the weather pattern to more typical January weather.

DC Area residents may forget that the first half of January 2018 was as cold as the first half of this month has been warm.  High temperatures remained at or below freezing on eight of the first 15 days of January 2018.  However, there was a major shift in the weather pattern.  Temperatures on 12 of the 16 days during the second half of January 2018 were warmer than average, with only one high temperature below 40°.  In that time, high temperatures reached 60°/+ on five days and that helped January 2018 finish within 0.3° of average, masking just how cold the first half of the month was.  

DC’s weather pattern will be the complete opposite this month with more seasonal to slightly cooler than average temperatures over the second half of the month.  Much like two years ago, that should help January 2020 finish with near average monthly temperatures.  That underscores how hard it is for the Mid-Atlantic Region to remain very warm or very cold during the month of January.  Typically, January is the coldest month of the year in the Nation’s Capital and features DC’s lowest average high and low temperatures.

It’s interesting to note that while DC has had seven of its 12 warmest months on record since 2010, none of them were January.  In fact, only one January in the last decade ranks among DC’s 15 warmest: January 2017 (11^th).  While dozens of record high temperatures were observed in the Nation’s Capital between 2010 and 2019, only two record low temperatures were recorded and neither were in January.

The last decade has featured a disproportionate amount of warm weather in the Nation’s Capital compared to earlier decades.  January has been relatively isolated from this trend with the majority of DC’s warmest January’s having occurred in or prior to 1950.  In fact, six of the last 10 January’s have been colder than average in the Nation’s Capital.

Although five of the last 10 January’s were snowier than average in the Nation’s Capital, not all of them were colder than average.  January 2019 was snowier than average, despite being more than a degree warmer than average.  That fact in conjunction with the cooler than average temperatures NOAA’s Climate Prediction Center expects over the final one to two weeks of the month should give hope to winter weather enthusiasts in the DC Metro Area.

DC’s Only Record Low Temperatures between 2010 and 2019 (Source: NOAA)

February 20, 2015: 5°
November 11, 2017: 26° (that tied the record low for the date)