As the DC/Baltimore area is just about past its normal period of freezing weather in the Spring, it has been one of the milder seasons regarding freezing temperatures. Historically, most locations outside of the downtown areas have had freezing temperatures into May but, as the extended forecast is currently not showing any cold weather into early May, this current season, which runs July 1, 2019 – June 30, 2020, has been a record to near-record mild period. The airport in Baltimore is currently at its least number of days reaching ≤32° and both National Airport and Dulles Airport are currently at second-least (see the data tables below). Both Baltimore and Washington have longer temperature histories when including their downtown locations but the climatic and geographic differences do not allow for a favorable comparison, hence only the airport data is being used here (note their individual periods of record).   

The Average number of days to reach freezing minimum temperatures at the three airports for their periods of record: Washington (National AP) is 68, Baltimore (BWI AP) 96, and Dulles AP 109, the latter two’s higher numbers indicating their suburban locations vs. the warmer urban location of National Airport. 

During its full period of record, Dulles Airport has an average first freeze on Oct. 16th and did manage to reach 33° on Oct. 19th this season but didn’t actually reach freezing until November 2nd, more than 2 weeks later than normal. Baltimore’s average first freeze is Oct. 28th, also reaching freezing on Nov. 2nd so only 5 days later than average. Washington National Airport, on the Potomac River in Virginia across from Washington, and located pretty much in the middle of the heat island of DC, has a much later average first freeze of November 13th, but managed to first hit freezing on November 9th, 5 days earlier than average. The earliest freeze dates at these airports are: National Airport on 10/20/1994 and 10/20/1972; Baltimore on 10/4/1974; and Dulles on 9/24/1983 and 9/24/1974.  

In the Spring, the latest average freeze dates are thus: National Airport is on March 28th, Baltimore on April 11th, and Dulles Airport is the latest of all on April 22nd. The latest freeze dates at these airports are: National Airport, 4/21/1956; Baltimore, 5/11/1966 (its only May freezing temperature); and Dulles, 5/22/2002. As we move into May the odds of freezing temperatures diminish greatly so it’s likely that the data in the tables below will remain as the final data for the current season, July 1, 2019 – June 30, 2020. If the data were to be superseded, this blog will be updated accordingly.

Of course, the majority of freezing temperatures normally occur during the three meteorological winter months (December, January, and February), but with Minimum Temperatures far above normal for these months this season, it was difficult for the months outside of this three-month period to catch up. In fact, Baltimore Minimum Temperatures for the 2019-2020 meteorological winter averaged 32.0° (a +5.6° departure), its all-time warmest since official records were moved from downtown in August 1950. Dulles Airport averaged 30.7° (+5.0° departure), its second-warmest, and National Airport averaged 35.2° (+4.6° departure), its 7th warmest (please see below for the monthly average temperatures for the current season).    

Incidentally, as far as freezing Maximum Temperatures, for the current season, not one of the three airports recorded a single day ≤32°, the first time that Dulles Airport has failed to have this occur. National Airport has only had this happen one other time (1997-1998) and for Baltimore it’s occurred two other times (1952-1953 and 1997-1998).  

 

I apologize for the small text and odd formatting on the tables below – trying to figure out how best to move them from Excel into WordPress. The formatting works better on the desktop version vs. mobile phone.  To enlarge the text on a desktop computer, simply depress the Ctrl key and simultaneously press the “+” (plus) key. To return to the previous size, simultaneously press the Ctrl key and the “-” (minus) key.

Cover Photo courtesy of Shutterstock.

 

 

TOP-10 LEAST NUMBER OF DAYS OF SEASONAL TEMPERATURES ≤32°

BALTIMORE, MARYLAND
Baltimore-Washington International Thurgood Marshall Airport
Period of Record: 1950-2020
Rank	Season	Jul	Aug	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Jun	Season Total
1	2019-2020	0	0	0	0	10	16	18	16	4	2	M	M	66
2	1994-1995	0	0	0	0	3	16	19	23	6	4	0	0	71
3	2016-2017	0	0	0	1	9	19	14	16	15	0	0	0	74
4	2015-2016	0	0	0	1	7	9	27	19	9	4	0	0	76
5	1952-1953	0	0	0	5	9	16	18	19	8	2	0	0	77
6 tie	2011-2012	0	0	0	2	7	21	25	16	7	1	0	0	79
6 tie	1971-1972	0	0	0	0	8	11	19	21	15	5	0	0	79
8	1972-1973	0	0	0	4	13	13	24	18	5	5	0	0	82
9 tie	1982-1983	0	0	0	1	10	17	25	21	6	3	0	0	83
9 tie	1970-1971	0	0	0	0	7	16	27	15	15	3	0	0	83
9 tie	1956-1957	0	0	0	1	13	11	28	17	9	4	0	0	83

 

WASHINGTON, DC
Washington Reagan National Airport
Period of Record: 1941-2020
Rank	Season	Jul	Aug	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Jun	Season Total
1	2011-2012	0	0	0	0	0	7	16	5	2	0	0	0	30
2	2019-2020	0	0	0	0	4	10	13	12	1	0	M	M	40
3 tie	2016-2017	0	0	0	0	1	12	8	8	12	0	0	0	41
3 tie	2007-2008	0	0	0	0	1	7	15	16	2	0	0	0	41
5 tie	2012-2013	0	0	0	0	2	5	14	13	7	1	0	0	42
5 tie	1997-1998	0	0	0	0	6	11	8	7	10	0	0	0	42
6	1948-1949	0	0	0	0	0	12	9	12	12	0	0	0	45
7	2001-2002	0	0	0	0	0	8	15	16	6	1	0	0	46
8 tie	2018-2019	0	0	0	0	6	8	18	10	5	0	0	0	47
8 tie	2015-2016	0	0	0	0	1	2	23	15	3	3	0	0	47
8 tie	1990-1991	0	0	0	0	1	10	19	13	4	0	0	0	47

 

DULLES, VIRGINIA
Washington-Dulles International Airport
Period of Record: 1961-2020
Rank	Season	Jul	Aug	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Jun	Season Total
1	2015-2016	0	0	0	2	9	9	26	19	9	5	0	0	79
2	2019-2020	0	0	0	0	16	19	20	17	6	2	M	M	80
3	2016-2017	0	0	0	1	12	22	14	16	15	2	0	0	82
4 tie	2011-2012	0	0	0	2	14	20	24	17	7	3	0	0	87
4 tie	2009-2010	0	0	0	0	6	24	25	25	6	1	0	0	87
6	2004-2005	0	0	0	1	9	21	18	20	18	2	1	0	90
7	2007-2008	0	0	0	2	10	18	25	24	12	2	0	0	93
8 tie	2005-2006	0	0	0	0	11	28	18	22	14	1	0	0	94
8 tie	1999-2000	0	0	0	1	9	22	25	19	13	5	0	0	94
10	1997-1998	0	0	0	8	12	25	19	12	15	5	0	0	96

 

 

MINIMUM TEMPERATURE DEPARTURES, NOV. 2019 – MARCH 2020

Baltimore – BWI

#1 Warmest Dec-Feb: 32.0° (+5.6° departure)

 

Month	Average Minimum Temperature	Departure from Normal
Nov.	34.3	-2.2
Dec.	31.5	+3.4
Jan.	31.7	+7.3
Feb.	32.7	+6.1
Mar.	40.8	+7.3

 

 

Washington, DC – National Airport

#7 Warmest Dec-Feb: 35.2° (+4.6° departure)

 

Month	Average Minimum Temperature	Departure from Normal
Nov.	38.2	-3.0
Dec.	34.9	+2.4
Jan.	35.0	+6.4
Feb.	35.8	+4.9
Mar.	44.3	+6.7

 

 

Dulles Airport

#2 Warmest Dec-Feb: 30.7° (+5.0° departure)

 

Month	Average Minimum Temperature	Departure from Normal
Nov.	31.9	-3.4
Dec.	30.2	+3.1
Jan.	30.2	+6.3
Feb.	31.6	+5.6
Mar.	39.7	+6.8

 

 

Data Source: Baltimore-Washington National Weather Service, Sterling, VA: https://w2.weather.gov/climate/xmacis.php?wfo=lwx

Freeze data tables through April 26, 2020.