The coldest air mass of the season will descend upon the D.C. region this weekend and temperatures will be cold enough to concern those with outdoor gardens and planted flowers.
A sharp cold front pushed west to east across the D.C. area Friday night — temperatures in its wake fell about 10 degrees as winds kicked up. The problems will arise overnight Saturday into early Sunday morning.
A combination of clear skies and dry air, along with rather moist ground and calm winds will allow frost to develop north and west of D.C. on Sunday morning. Temperatures will drop to the freezing mark for a few hours close to daybreak on Sunday.
Areas inside the Capital Beltway and along and east of Interstate 95 will be spared any frost, as temperatures only drop to around 40.
The best practice during a Frost Advisory, which is expected to be issued for early Sunday along and west of the Blue Ridge, is to either cover tender vegetation like flowers or bring flower pots inside.
It usually takes a hard freeze with temperatures in the 20s for several hours to cause permanent damage to flowers and crops. That type of cold is responsible for ending the growing season and won’t occur just yet.
Historically, the D.C. area doesn’t have its first frost until the sometime between Nov. 8 and Nov. 12, followed by a hard freeze that ends the growing season just before Thanksgiving.
However, the frost and freeze season is always earlier by a few weeks along and west of the Blue Ridge. The first frost occurs in mid-October, followed by the first autumn freeze just before Halloween.
The pattern going forward through the remainder of the October will bring frequent cold fronts across the D.C. region, with a likelihood for the killing frost or hard freeze to occur earlier than usual this year.