Putting March 2018 Into Perspective

March 2018 will finish as cooler than February in Washington, D.C. for a second consecutive year.  That’s the first time it’s happened in consecutive years since 1890-1891.  Through March 29, DC’s average monthly temperature (combining daily high and low temperatures) is 42.8° (well below the March average of 46.8°). 

The first 60°/+ temperature of the month didn’t occur until yesterday when the high temperature reached 78° at National Airport.  That’s the second latest first 60° March day in the Nation’s Capital on record.  Ironically, January and February each had eight days when high temperatures reached at 60° or warmer.

While no record cold occurred in the Nation’s Capital this month, the cooler than average weather was very persistent.  High temperatures have been below average on 23 days since March 1.  Washingtonians also had more days in March where low temperatures were at or below freezing (eight) than February (six).

February was warmer than average in both 1890 and 1891 in the Nation’s Capital and March was considerably cooler average.  However, February 2017 and February 2018 were not only warmer than average, but were DC’s warmest and third warmest February’s on record.  March 2017 was 0.4° warmer than average, but still finished 0.5° cooler than February 2017 because the month was so warm in Washington, D.C.  By comparison, this March has been significantly cooler than average in Washington, D.C.  Consequently, there will be a much larger difference in temperature between the average monthly temperatures of February (45.3°) and March 2018 (42.8°). 

DC’s warmest temperature so far this month occurred yesterday (77°) while March’s coldest temperature (31°) occurred four times.  The high temperature of 36° on March 21 was significantly below the average high of 58°.  It was DC’s coldest high temperature since February 3 (also 36°).  March’s cooler than average temperatures have caused the National Park Service to push back the dates of the expected peak bloom of the cherry blossoms on the Tidal Basin to April 8 – 12.  Peak bloom is defined as when 70% of the blossoms are out.

March 2018 will finish as a snowier than average month (4.5” is more than triple DC’s March average of 1.3”).  However, this month will finish with below average rainfall with only 1.92” of rain (that includes liquid equivalent of the snowfall) since March 1 in Washington, D.C.  That’s not unusual since 10 of the last 20 Marchs have been drier than average in Washington, D.C.  However, March 2018 is the sixth consecutive March that Washingtonians have had measurable snowfall.  The Nation’s Capital has also had above average snowfall in five of the last six Marchs (including this month).

Chilly March Weather and DC’s Cherry Blossoms

March Snow in the DC Metro Area

DC Area residents have endured some unusually chilly weather for most of March.  The Nation’s Capital has had 13 days with high temperatures in the 40s through March 26.  That’s despite average high temperatures in the 50s for almost the entire month.  DC’s warmest temperature so far this month was 59° that occurred twice.  

Temperatures in Washington, D.C. could reach 60° for the first time this month tomorrow, March 28.  It’s very unusual for DC’s first 60° March day not to occur until so late in the month.  That’s after January and February each had eight days with high temperatures of at least 60°.  In addition to having eight days with high temperatures in the 60s, DC also had another eight January days when high temperatures remained at or below 32°.  Last month was the third warmest February on record in the Nation’s Capital.  DC also experienced its earliest 80° day on record (82° on February 21).

Not only have high temperatures been below average on all but five days so far this month, but Washingtonians also experienced some unusual snowfall.  While not among DC’s ten largest March snowfalls, the 4.1” of snow that occurred on March 21 was the most to occur on or after March 20 since 1964.  With this month’s total of 4.5” of snow, March 2018 is only the 24^th time since 1888 that March is the snowiest month of the season.  However, March has been the snowiest month of the winter five times in the last ten years in Washington, D.C.  According to NOAA, the Nation’s Capital averages 1.3” of snow in March.

Low temperatures this month have been at or below freezing on eight days in Washington, D.C.  That’s compared to only six such days during all of February.  Last month finished 6.3° warmer than average while March has been 4.1° colder than average through March 26.  The net swing of more than 10° can help explain why this month seems significantly colder than normal in the Nation’s Capital.

Despite this month’s unusually chilly weather, no record cold has occurred in the Nation’s Capital.  The below average temperatures this month have caused the expected peak bloom of the cherry blossoms to be pushed back twice.  Following the warmer than average February, the original forecast from the National Park Service called for peak bloom of the cherry blossoms to occur between March 17 and March 20.  However, peak bloom is now expected to occur between April 8 and April 12.  Peak bloom occurs when 70% of the cherry blossoms are out.

Palm Sunday and Severe Weather

March 12, 2006 Severe Weather  (Source: NOAA)

Severe weather is defined by the National Weather Service as a thunderstorm that contains any of the following, hail at least 1” in diameter or greater, wind gusts of at least 58 mph or a tornado.  The United States experiences an uptick in the frequency of severe weather during the month of March.  There have been several significant severe weather outbreaks in the United States during the March over the last 25 years that heighten the importance of public awareness.

2017:  A significant severe weather outbreak occurred on March 6 last year from Oklahoma to Wisconsin and Nebraska to Indiana.  Of the more than 600 reported cases of severe weather, there were 79 confirmed tornadoes.  While dozen injuries were reported following the tornadoes, there were no fatalities.  

2007: Severe weather in March is more common in the southeast close to the Gulf Coast where the weather is typically warmer and more humid.  For example, on March 1, 2007 when a severe weather outbreak occurred that was concentrated in Mississippi, Georgia and north Florida.  Of the nearly 300 severe weather reports, there were 68 confirmed tornadoes that claimed 20 lives.  

2006: One of the larger March tornado outbreaks on record occurred on March 12 with nearly 700 severe weather reports.  That includes 140 confirmed tornadoes that were concentrated in the state of Missouri.  These tornadoes resulted in four fatalities in addition to several dozen injuries.  

Between 1990 and 2000 there were several other memorable March severe weather outbreaks.  On March 28, 2000, an F3 tornado caused widespread damage in Fort Worth, Texas with two fatalities.  Palm Sunday occurred on March 27 in 1994.  That’s when more than two dozen tornadoes developed in the southeast United States and claimed 40 lives with nearly 500 reported injuries.  

Tornadoes were initially ranked on the “Fujita Scale” (from F0 to F5), but have been ranked on the updated or “Enhanced Fujita Scale” (EF-0 to an EF-5) since 2007.  The strongest tornadoes, ranked an F5 or an EF5, are exceedingly rare.  The last F5 or EF5 tornado to occur in the United States during the month of March was on March 13, 1990 in the state of Kansas.  Overall, there haven’t been any EF5 tornadoes anywhere in the United States since May 2013.  The strongest tornadoes to occur in Maryland and Virginia were F4’s.  

Severe weather is more common in the Mid-Atlantic Region during the late-spring and summer months.  However, there have been some occasional March days with severe weather in DC Metro Area.

Spring Snow in the DC Metro Area

Area snow lovers got their long-awaited taste of sledable snow yesterday.  It was DC’s largest snowfall since the record January 2016 snow event.  Many area school districts either closed or opened late yesterday and this morning as a result.  Here are some snow totals for Wednesday’s event.  Please add your totals as a comment.

Washington, D.C.

National Zoo – 4.1”

Maryland

Frostburg – 11.0”
Westminster – 10.2”
Mount Airy – 8.0”
Columbia – 7.0”
Greenbelt – 6.9”
Poolesville – 4.0”
Bethesda – 3.5”
La Plata – 3.5”

Virginia

Harrisonburg – 6.0”
Dulles Airport – 5.3”
Chantilly – 5.0”
Reston – 5.0”
National Airport – 4.1”
Alexandria – 3.5”

Late March Snow in DC

March 21 Snowfall Forecast  (Source: WUSA9)

Accumulating snow in the second half of March is relatively rare in the Nation’s Capital.  That said, the DC Metro Area is poised to experience its largest accumulating snow event since the record January 2016 blizzard.  Several inches are likely tomorrow inside I-495.

Washingtonians had very little snowfall last winter and for much of this season.  In fact, the meteorological winter of 2017-2018 (December 1 through February 28) finished with only 3.3” or roughly 20% of the seasonal average of 15.4”.  However, a coastal storm has developed in the ideal position to bring the Mid-Atlantic Region its largest snowfall in more than two years.  Although Washington, D.C. averages 1.3” of snow in March, significant snowfall is quite rare in the second half of March.  That’s because there are environmental and meteorological factors which combine to make significant snow hard to come by (e.g. increasing sun angle).  

March is the first month of meteorological spring (March 1 through May 31) and the sun angle is a lot higher than in December or January.  That’s important because it leads to warmer temperatures – even on cloudy days.  Average high and low temperatures in Washington, D.C. range from 51°/34° on March 1 to 61°/42° on March 31. 

Large temperature fluctuations are quite common in the DC Metro Area during the month of March.  For example, it was 70° in Washington, D.C. on March 15, 2014, before temperatures fell dramatically late on March 16.  St. Patrick’s Day 2014 was a frigid and snowy day in the Nation’s Capital with a total of 7.2” of snow, which began late on March 16.  However, that snow wasn’t around long as temperatures were in the low 60s on March 20, 2014.

There are no 60° temperatures expected in the Nation’s Capital until next week at the earliest.  That could make this March unusual for another reason.  Through March 20, DC’s average monthly temperature (combining daily high and low temperatures) is more than 2° below normal at 42.4°.  That makes it quite likely this month will finish cooler than average and cooler than February (45.3°).  March 2017 was cooler than February 2017 and that hasn’t happened in consecutive years since 1890-1891, according to National Weather Service data.  

Last month was DC’s third warmest February on record, so this month feels especially chilly by comparison.  Washingtonians experienced their earliest 80° temperature on record on February 21, 2018, but the warmest temperature this month has only been 59° on March 1.  My colleagues and I on the WUSA9 Weather Team will continue to refine the forecast both on-air and on the WUSA9 mobile app.

Washington, D.C.’s largest snowfalls in the second half of March:

March 27-28, 1891: 12”
March 28-29, 1942: 11.5”
March 15-16, 1900: 10”
March 14-16, 1937: 8”
March 16-17, 2014: 7.2”

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March 21 Daily Snowfall Records for the DC Metro Area

Washington, D.C. (Reagan National Airport - DCA): 5.3” (1924)
Dulles Airport, Sterling, VA (IAD): 2.3” (1964)
Baltimore, MD (BWI Airport): 9.7” (1964)