Freeze weather warning

Three weeks behind average, and a several days after the wintry towns of Van Nuys, California. and Houston, Texas., Reagan National Airport (DCA) finally hit freezing this weekend! This is only the tenth time in 140 years of daily temperature records that the first freeze at DCA waited until Dec. It’s also the third latest (tied) on record. Only 1980 (12/14) and 2001 (12/22) have seen later freezes, and 2011 ties with 1978 with both first freezes happening on December 10.


While this year’s first freezes along Potomac river banks (at DCA) took their time, that’s not the case elsewhere. Through today, Dulles has now seen 25 lows of freezing or below and Baltimore-Washington Airport has witnessed 18. That compares to DCA’s 3 season-to-date — the 10th snuck one in at 11:59 p.m. (so one night counted for two days).


Historically , a December first freeze is somewhat unusual, even by less forgiving (or, increasingly warm) 1981-2010 standards. As noted in “When should the Washington, D.C. area expect to see its first freeze of the cold season?”, only 20% of these most recent seasons experienced their first freeze in December. However, considering there was only one (post November first freezes) prior to 1975 — far back in 1948 — perhaps we should get used to it being more common.


In 2010, thanks to the earliest final (spring) freeze on record, we nearly reached the record length of time without a freeze at D.C. with 274 days (compared to the leader, 275, in 1980). This year Washington entered the top 10 yet again, finishing tied at 7th with 2009. That seems like quite an unusual accomplishment, except when factoring in a full half of the top 10 freeze free periods have occurred since 2001.


When comparing to the other area climate locations, at Dulles and Baltimore-Washington airports, there are stark differences. This should be expected, at least partly due to DCA’s location on the river with no elevation, and its proximity to the urban concrete jungle.


But, with more than 5 weeks in between the earliest at DCA and at the other locations — October 30 for both — one has to wonder how useful a metric the "official" first Washington D.C. freeze is for the area.


Maybe you can make fun of your friends that see a later freeze than National. Caution: that might instantly label you a weather nerd.


# OF DAYS WITH A FREEZE THRU 12/12


DCA (3): Dec (3); Nov (0); Oct (0) - Earliest: Dec 10 - Lowest: 29 on 12/11 and 12/12


Dulles (25): Dec (9); Nov (14); Oct (2) - Earliest: Oct 30 - Lowest: 19 on 12/12


BWI (18): Dec (9); Nov (7); Oct (2) - Earliest: Oct 30 - Lowest: 22 on 12/12