Winter Has Returned

Today and tomorrow will be cold, wet and raw in the DC Metro Area.  Communities north and west of town will see more sleet and freezing rain than inside I-495.  Areas south and east of town will primarily see just rain.  That’s the result of a complex weather pattern with temperatures that aren’t cold enough to support a pure snow event in the Nation’s Capital.  Temperatures were much colder on Saturday and Sunday than they were last week and helped surface temperatures fall, making conditions more favorable for freezing rain.  That’s especially true in areas north and west of town (more specifically areas west of I-81 in Virginia and north of I-70 in Maryland).

The transition back to winter has been marked in the Nation’s Capital.  The first week of February was quite warm with high temperatures of at least 56° on five consecutive days from February 3 – February 8.  Washingtonians experienced a record high of 74° last Tuesday, February 5.  That was DC’s first 70° temperature since November 2 (73°).  It was also DC’s warmest stretch of weather in the first half of February since 2009.

February is DC’s snowiest month of the year on average with six of the top 10 snowfalls on record (such as the February 1899 and 1979 snow events).  However, things have changed in recent decades.  While 12 of the last 20 February’s have been warmer than average in Washington, D.C. only six of the last 20 have featured above average snowfall.  Moreover, six of DC’s 10 warmest February’s have occurred just since 1990.  In fact, 2017 and 2018 featured DC’s warmest and third warmest February on record.  That illustrates that while the right ingredients can come together to produce epic snowfall or record cold, the trend in recent years has been for warmer than average temperatures. 

The big difference in the last 20 years has been with overall temperatures.  While six of the last 10 February’s have been warmer than average, there were three consecutive February’s (2013-2015) that were colder than average in the Nation’s Capital.  That was the first such occurrence since 1993-1996, when four consecutive colder than average February’s occurred.  Nine of DC’s 10 coldest February’s on record occurred prior to 1940.  

The Nation’s Capital has had 12 record highs in February, with just one record low temperature in the last 20 years.  Dulles Airport has had a closer ratio in that time, with 12 record February high temperatures compared to seven record low temperatures.  That can partially be attributed to a more significant urban heat island effect within DC compared to where Dulles Airport is located in Sterling, Virginia.  While 14 of the last 20 February’s have been drier than average in the Nation’s Capital, a very wet week is on tap in Washington, D.C.  NOAA’s monthly outlook for February is a 40% chance for wetter than average conditions in the DC Metro Area.

Washington, D.C.’s Warmest February’s by average Temperature (Combining Daily High and Low Temperatures - Source: National Weather Service)

1.  2017: 47.7°
2.  1976: 46.9°
3.  2018: 45.3°
4.  1990: 45.2°
5.  1997: 44.7°
6.  2012: 44.4°
7.  1984, 1949: 43.8°
9.  1981: 43.7°
10.  1954: 43.5°

---

Washington, D.C.’s Coldest February’s

1.  1934: 24.6°
2.  1895: 26.2°
3.  1905: 26.4°
4.  1885: 26.9°
5.  1899: 27.4°
6.  1979, 1904: 28.4°
8.  1875: 28.8°
9.  1936: 29.6°
10.  1902, 1901: 29.8°
12.  1914: 30.1°
13.  1907: 30.2°
14.  2015: 30.3°
15.  2007: 30.9°

Record Heat Surpasses Record Cold

Although winter will make a return tonight with colder, more seasonal temperatures this weekend, DC Area residents enjoyed this week’s record-setting warmth.  In fact, Washingtonians had high temperatures of at least 55° on six consecutive days this week (February 3 – 8).  That’s been a nice change for all but those who want snowfall.

The Nation’s Capital set a record high of 74° on February 5, which was almost 30° above the average high for the date of 45°.  It was also the third consecutive year that Washingtonians experienced their first 70° day of the year on or prior to February 15.  NOAA released a report this week that said 2018 was the fourth warmest year on record globally.  To add to that, “Nine of the 10 warmest years have occurred since 2005, with the last five years comprising the five hottest,” according to NOAA.

Washington, D.C., has had a total of 85 record high temperatures over the last 20 years (1999-2018).  That’s compared to only five record low temperatures.  Over the same time period, the Nation’s Capital had 184 record high/low temperatures.  That means the coolest temperature of the day was significantly warmer than the average low temperature.  At the same time, DC had only 20 record low high temperatures (daily high temperatures that were much cooler than average) for a rough nine to one ratio.

At Dulles Airport, where the urban heat island effect has less of an impact, there was a similar trend.  For example, Dulles had 188 record high temperatures in the last 20 years compared to 50 record low temperatures.  Dulles also had 310 record high low temperatures compared to 144 record low high temperatures.

These global temperature trends coincide with an increased amount of urbanization and development, as well as an increase in greenhouse gas emissions.  Locally, the much higher frequency of record heat compared to record cold can also be attributed to an increasing urban heat island effect.  The population density is much greater in the DC Metro Area today compared to the 1980s and 1990s.  That also means more people were able to enjoy the spring-like temperatures that occurred this week.

National Weather Person’s Day

DC Area Residents enjoy record warmth this February 5 !

Washingtonians have experienced a high degree of weather variability during the month of February.  The first week of February has featured very diverse weather events over just the last decade.

2017:  What turned out to be DC’s warmest February on record got off to a very warm start with six of the first eight days being warmer than average.  Record highs in the 70s occurred on February 7 and February 8.  That’s similar to this week since the Nation’s Capital set a new record high of 72° this afternoon breaking the existing record (70°) that had stood since 1890.  February 2017 was also DC’s sixth driest February on record.

2015:  In 2015, February also had a milder than average start but it became DC’s coldest since 1979.  A total of seven days had high temperatures at or below 32°.  A record low of 5° was set on February 20 that was DC’s coldest February temperature, overall, since February 2, 1961 (4°).  Unlike the dry months of February 2017 and 2018, this February was snowier than average (5.7”) with 9.8”.

2010:  This February will forever be synonymous with the record-setting storm that began nine years ago today, “Snowageddon.”  It is DC’s fourth largest snowstorm (currently tied with the January 2016 blizzard) and produced 17.8” of snow at National Airport.  Snowfall totals of 20” to 30” were common in the DC Metro Area.  The 2009-2010 winter season became DC’s snowiest on record (56.1”). 

1996:  This was DC’s third snowiest winter with 46”.  Washingtonians experienced some of the coldest weather in recent memory in early February.  The Nation’s Capital had five consecutive days to start the month with high temperatures below freezing.  No record lows were observed downtown, but Dulles Airport had record low temperatures of -10° and -9°, respectively, on February 4 and 5.

February 5 is also National Weatherperson’s Day, which is designed to recognize and honor everyone who works in the fields of meteorology and atmospheric science.  There are many facets to the field of meteorology from forecasting in both the public and private sector (e.g., for airlines, agriculture and other weather dependent industries) to broadcast meteorologists, researchers and teachers.  Today’s the day to recognize what meteorologists do to promote awareness and public safety.

Did the Groundhog see his Shadow ?

Those tired of this week’s frigid cold and snow should be pleased that Pennsylvania’s “Punxsutawney Phil” did not see his shadow this morning – meaning an early spring.  Folklore aside, it will actually feel more like spring the next few days.  People shouldn’t have too much faith in “Phil” since he’s only been accurate 39% of the time.  

Although February got off to a frigid start yesterday with temperatures in the low to mid 20s across the DC Metro Area with light snow, a major pattern shift is in the cards.  While no record cold occurred downtown, DC’s high and low temperature of 25°/10° on January 31 was the coldest day in the Nation’s Capital since January 7, 2018 (23°/8°).  Meanwhile, Dulles Airport’s low temperature of -2° on Thursday was its coldest temperature since February 24, 2015 (-4°).  High temperatures will, however, be much warmer over the upcoming week.  

Average temperatures in the Nation’s Capital range from 44°/29° on February 1 to 51°/33° on February 28.  DC’s warmest temperature on record for the month occurred on February 25, 1930 (84°).  Meanwhile, DC’s coldest February temperature of -15° was on February 11, 1899.  On February 21 last year, DC’s high temperature reached 82°.  That was significant for two reasons: 1) It a record high temperature for the date; and 2) It was the earliest in the year that Washington, D.C. had its first 80° temperature.

Twelve of the last 20 February’s have been warmer than average in Washington, D.C. dating back to 1999.  However, Washingtonians experienced three consecutive colder than average February’s from 2013 through 2015, the longest such streak since 1993 – 1996.  Over the last 20 years, there has also been a combined 20 record high and record high-low temperatures in Washington, D.C., with only one record low temperature (5° on February 20, 2015).  That coincides with an increased urban heat island effect, as urbanization and development have increased dramatically in and around the Nation’s Capital in recent decades.  

February is the snowiest month of the year in Washington, D.C. with a monthly average of 5.7”.  Six of DC’s 10 largest snowstorms have occurred in February, including some epic storms as “Snowmageddon” in 2010 and the President’s Day weekend storms of 1979, 1983 and 2003.  However, 14 of the last 20 February’s have had below average snowfall.  Only six of the last 20 February’s have been rainier than average (2.62”) dating back to 1999.  

NOAA says there’s an equal chance for February 2019 to finish with above or below average temperatures in the immediate DC Metro area, with a 40% chance for a wetter than average month.  After a warmer than average start to February, colder than average weather is expected to return by the middle of the month.  Periods of above and below average temperatures of similar duration tend to produce near average temperatures as a whole.