Spring Gets Off to a Cool and Wet Start in the Nation's Capital

NOAA's Precipitation Outlook for the Final Week of March

Although spring officially arrives in March, this month often feels more like winter in the Nation’s Capital.  March 2019 was no exception, with accumulating snow on March 1 followed by colder than average temperatures on nine of the first 10 days of the month.  That was followed by a stretch where temperatures were above average on six of the subsequent 10 days through March 20.  This has produced a monthly average temperature (combining daily high and low temperatures) 0.5° cooler than average at National Airport (DC’s official weather reporting site).

Including yesterday’s drenching rainfall, there have been 10 days with precipitation so far this dreary month.  The 1.96” of rain yesterday was DC’s highest daily rainfall total since December 15 (2.55”).  Dulles Airport experienced a record 2.69” of rain, more than double the previous March 21 rainfall record of 1.29” from 2000.  It was also the largest daily rainfall total on record during the month of March at Dulles Airport.  With yesterday’s rain, DC has had 3.87” of rain since March 1 (greater than the average of 3.48” for the entire month).  Although Washingtonians had a chilly and wet first full day of spring yesterday, it pales in comparison to what DC residents had a year ago.

DC residents experienced the largest snowfall of the 2017-2018 winter season on March 21, 2018, when a total of 4.1” of snow fell at National Airport.  Although accumulating snowfall is less common in March, DC averages 1.3” of March snowfall.   March has also been DC’s snowiest month in four of the last seven years.  Including the 0.3” of snow on March 1, 2019, Washington, D.C. has had measurable snowfall in seven consecutive March’s – the longest such streak on record. 

NOAA keeps weather records for the United States and updates its climate averages by decade.  The 1.3” March snowfall average in the Nation’s Capital is based on NOAA’s 30-year average for the period from 1981-2010.  While NOAA uses a 30-year average to determine temperature and precipitation information, they are updated every decade.  That means at the end of 2020, NOAA will update its 30-year average to use weather data from 1991-2020.

Temperatures have also shown an interesting trend in the Nation’s Capital in recent years.  While DC residents experienced the warmest and fourth warmest March’s on record in 2012 and 2016, March 2013 – March 2015 were each colder than average.  That was the first time since 1992-1994 that DC had at least three consecutive colder than average March’s.  March 2018 was significant for being DC’s first cooler and drier than average March since 2013.  Meanwhile, this month will finish with near average temperatures and an increased potential for drier than average conditions, according to NOAA’s outlook for March 27 – 31. 

What Was the “Tri-State Tornado?”

(Source: NOAA)

While the three most active months of the year in the United States for severe weather and tornadoes are April, May and June, the month of March is also important.  In fact, the deadliest tornado on record in the United States occurred in March almost 100 years ago.  There have been several significant severe weather outbreaks in March more recently.  

A deadly tornado outbreak earlier this month on March 3 claimed 23 lives in Beauregard, Alabama.  Another deadly March severe weather outbreak in the United States was in 2012.  There were over 130 tornadoes on March 2, 2012 as part of an outbreak that produced nearly 700 total cases of severe weather (hail 1”/+ in diameter, wind gusts of at least 58 mph or a tornado).  This severe weather outbreak covered an unusually large geographic area from Texas to West Virginia.  The deadliest tornado during this outbreak was on the ground for 34 miles in Kentucky where eight lives were lost.

The “Atlanta Outbreak” occurred on March 15, 2008 and a total of 51 tornadoes developed.  These tornadoes caused one fatality and 19 injuries.  Tornadoes can strike urban and suburban areas just as easily as rural ones.  Over just the last two decades, there have been tornadoes in major urban areas such as Nashville, Salt Lake City, Atlanta, Chicago and even Los Angeles. 

A total of 20 fatalities were reported in a March 1, 2007 severe weather outbreak that spanned from Illinois to Florida.  Nearly six dozen tornadoes occurred during this event.  Meanwhile, a year earlier another significant severe weather outbreak occurred on March 12, 2006.  Of the nearly 700 severe weather reports, 140 of them were tornadoes that were concentrated in Missouri and Illinois.  These tornadoes claimed four lives and caused 90 injuries.

The “Tri-State Tornado” as it was dubbed occurred on March 18, 1925.  It had a long track across parts of Illinois, Missouri and Indiana.  At one point, this tornado was estimated to have attained F5 intensity on the Fujita Scale with wind speeds of greater than 300 mph.  It leveled everything in its path and became the deadliest tornado on record with 695 fatalities.  According to the National Weather Service, this tornado was on the ground for three and a half hours and destroyed 15,000 homes.

Severe weather is more common along the U.S. Gulf Coast in March.  That’s because the weather in March tends to be warmer and more humid the farther south and east you travel.  Later in the spring as the continental United States sees milder temperatures, severe weather becomes more common over a larger geographic area. 

Dramatic DC Weather

Friday’s high temperature of 78° was DC’s warmest temperature since it was 83° on October 11, 2018.  Although it was significantly warmer than DC’s average high temperature on March 15 of 56°, Washingtonians fell short of breaking yesterday’s record high of 82°.

Once the cold front passed through last night, there was a precipitous drop in both temperature and relative humidity.  For example, at National Airport the winds were SW at 13 MPH with a temperature and dewpoint temperature of 70° and 59°, respectively, at 9:00 PM last night.  However, by 10:00 PM the winds were NW at 18 and gusting to 26 MPH.  Consequently, the dewpoint temperature had dropped to 36° and the temperature began to fall.  The significant drop in the dewpoint led to a steep drop in relative humidity from 68% to 29% between 9:00 PM and 10:00 PM last night.  

Washingtonians have averaged four days in March with high temperatures in the 70s since 1993.  The highs of 75° and 78° on March 14-15 were the first case of consecutive high temperatures in the 70s since November 1-2, 2018.  Since the cold front passed through the Nation’s Capital last night, temperatures fell from 70° at 10:00 PM to 49° by 5:00 AM.  Yesterday’s low temperature of 57° at National Airport didn’t occur until 11:59 PM.  That prevented DC residents from setting a new record high-low temperature for March 15.  The existing record for March 15 remains 60° from 1990.  

A “high-low” or “max-min” temperature means the low temperature on a particular day was unusually warm.  There are parallels between March 15, 2019 and March 15, 2014.  The high temperature in the Nation’s Capital on March 15, 2014 was 70°.  However, DC residents had a frigid St. Patrick’s Day with a high temperature of only 32° on March 17, 2014.  That coincided with 7.2” of snowfall from March 16-17.  By comparison, high temperatures this weekend will remain in the 50s.  

Weather enthusiasts are generally happy with the month of March as there’s often something for everyone.  Measurable March snowfall has occurred in DC in seven consecutive March’s, dating back to 2013.  At the same time, Washingtonians can also expect early summer-like warmth in March.  DC’s warmest March occurred relatively recently in 2012 and featured four days with high temperatures in the 80s and no temperatures at or below freezing. 

Weather Quiz

DC’s warmest daily average high temperature is 61° on March 29 – 31.  What is Washington, D.C.’s warmest March temperature on record ? 

A.  85°

B.  89°

C.  90°

D.  93°

Exciting March Weather

"Superstorm of 1993" Snow in the Mid-Atlantic  (Source: NOAA)

The month of March often produces a high degree of weather variability across the United States.  No place is that more true than in the DC Metro Area.  Longtime Washingtonians know March can pivot from cold and snow to record warmth and severe weather.

Although only 0.3” of snow fell in Washington, D.C. on March 1, it was significant since it made March 2019 the seventh consecutive March that accumulating snowfall has occurred.  While the “coldest” daily average high/low temperatures in the Nation’s Capital are above freezing (51°/34°) on March 1, DC averages 1.3” of snow in March.  To add to that, March has been DC’s snowiest month in four of the last six years.

By coincidence, today is the 26^th anniversary of the “Superstorm of 1993” that brought havoc to the eastern United States from Florida to New England.  Record snowfall occurred as far south as Mississippi and Georgia.  The 1993 storm remains the ninth largest snowstorm on record at Dulles Airport in Sterling, VA with 14.1”.  Since the snow changed to sleet at the height of the storm downtown, the overall accumulation in Washington, D.C. was only 6.6”.

Large temperature swings are quite common in March, as well.  For example, DC residents enjoyed a spring-like high temperature of 70° on March 15, 2014, but snow fell the next evening with a high of only 32° on March 17, 2014.  A total of 7.2” of snow accumulated in Washington, D.C. on March 16-17, 2014.

While March 2014 was DC’s snowiest since 1960, March 2012 and March 2016 were DC’s warmest and fourth warmest March’s on record.  Washingtonians experienced four days of high temperatures in the 80s in March 2012 and 10 days in the 70s in both March 2012 and March 2016.  The warmest temperature in the Nation’s Capital so far this March was 62° on March 11.  

Meanwhile, large swings in temperature help create favorable conditions for thunderstorms. While severe thunderstorms aren’t as common in the United States during the month of March as later in the spring, they sometimes occur.  March severe weather is more likely to occur in the southeastern United States as happened in Florida during the 1993 Superstorm.  More recently, a severe weather outbreak on March 3, 2019, produced dozens of tornadoes from northern Florida to South Carolina.  That included a rare EF-4 tornado which caused 23 fatalities in Lee County, Alabama.  

Although infrequent, the DC Metro Area has experienced severe March weather.  On March 10, 2011, two weak tornadoes touched down in northern Virginia.  Just last year, DC residents experienced a powerful wind event as an area of low pressure rapidly intensified as it departed the region.  Consequently, there were some damaging wind gusts that met severe criteria (58 mph/+).  However, gusty winds outside thunderstorms are not officially “severe,” regardless of whether or not any damage occurs.

Winds of Change

Below Average Temperatures Expected Again March 17 - 23  Source: NOAA

March 2019 has gotten off to a very cold, almost winter-like start in the Nation’s Capital.  That’s not unusual as March is a transitional weather month that often sees large swings in temperature and precipitation type.  In fact, March often features more weather diversity than any other month in the DC Metro Region.

This month has already had accumulating snowfall of 0.3” at National Airport, DC’s official weather reporting site on March 1.  That was followed by five consecutive days of low temperatures at or below freezing.  March 2019 has also been a wet month so far with measurable precipitation on seven of the first 10 days, including today.  Fortunately, for those ready for spring, there’s going to be a major shift in the weather pattern this week.

High temperatures are poised to reach the 60s for much of the DC Metro area today, depending on how much sun breaks through the cloud cover.  The first nine days of March have been colder than average and prior to today, DC had not even been 50° since February 28.  For a sense of perspective, DC’s average high/low temperatures on March 10 are 54°/36°.  Since 1993, it has averaged 1-2 days with high temperatures in the 30s.  So far this month, DC has had two days with highs in the 30s, while the seven other days all had below average high temperatures in the 40s.  

Spring-like weather has been slow to arrive this March, with no temperatures in the 60s in the Nation’s Capital since February 24 (63°).  As chilly as this month has been, no record cold has occurred.  March 2014 and March 2015 each got off to an even colder than average start in Washington, D.C.  In fact, March 2014 became DC’s snowiest March since 1960, with 12.7” at National Airport.  March 6, 2015 was the last time DC had a March high temperature that remained below freezing (30°).

Six of the last 10 March’s have been colder than average in the Nation’s Capital, including three consecutive ones from 2013 – 2015.  There have been some notable exceptions, however, with March 2012 and March 2016 being DC’s warmest and third warmest on record.  While DC has already experienced 70° warmth this year (a record high of 74° on February 5), the last 70° March temperature was on March 30, 2018 (77°).  By comparison, DC’s last 80° March temperature occurred on March 1, 2017 (80°).

NOAA predicts March has a 33% chance of finishing colder than average in the DC Metro Area.  Temperatures, however, will feel more like spring this week with lots of 50s and 60s on tap.  Below average temperatures are expected to return the week of March 17 – 23.  Large swings in temperature and precipitation type are what make March weather so fascinating in the Nation’s Capital ! 

Deadly March Weather

The severe weather outbreak this past Sunday, March 3 was the deadliest in the United States since 2013.  Nearly three dozen tornadoes have already been confirmed across the southeastern United States from Alabama to South Carolina.  Sunday’s deadliest tornado initially touched down in Macon County, Alabama and grew into a rare EF-4 tornado with winds of 170 mph.  It caused 23 fatalities in the small town of Beauregard, Alabama about 60 miles east of Birmingham.

Sunday’s tornado in Beauregard also became Alabama’s deadliest March tornado since the Palm Sunday outbreak on March 27, 1994.  That’s when at least 22 fatalities were reported in an F4 tornado that passed through the small town of Goshen, Alabama.  It’s important to distinguish between the EF-4 that occurred this past Sunday and the F4 that was reported 25 years ago.  Back in the 1970s, tornado intensity was measured on the Fujita Scale that went from a F0 tornado with wind speeds of 40 mph – 72 mph to an F5 tornado (261 mph – 318 mph).  However, in 2007 the revised “Enhanced Fujita Scale” ranks a minimal tornado an EF-0 with wind speeds of 65 mph – 85 mph.  An EF-5 tornado has wind speeds of 200 mph or greater.

In addition to the more than 30 confirmed tornadoes that occurred during the March 3, 2019 severe weather outbreak, there were numerous reports of severe wind gusts (58 mph/+) and severe hail (1”/+ in diameter).  By comparison, the largest March severe weather outbreak in all of last year occurred on March 19.  On that day, there were 28 confirmed tornadoes in the southeastern United States without any fatalities.

Due to its unique geography, the United States sees more tornadoes in an average year than any other country in the world.  According to the National Centers for Environmental Information, the United States averages 1,253 tornadoes per year for the period from 1991-2010.  The month of March is the sixth busiest month of the year for tornadoes, with an annual average of 80.  The months of April through August all have a higher average number of tornadoes than March.  

March is typically when the weather across the central and southern United States starts to warm up and become more spring-like.  Consequently, the average number of tornadoes increases dramatically from only 29 in February to the March average of 80.  Following the fall and winter months when severe weather and tornadoes are few and far between, the uptick in March is noteworthy.  That’s why it’s vital to listen to the latest weather forecasts from your favorite local meteorologists.