Brandywine climate

Brandywine Frost Dates and Growing Season

NOAA 1991-2020 normals for Upper Marlboro 3 Nnw, 18.6 km from Brandywine, elevation 130 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Upper Marlboro 3 Nnw. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 9 and the first fall freeze around October 29, a growing season of about 203 days.

Median at 36°F
last April 24, first October 19
Median at 32°F
last April 9, first October 29
Median at 28°F
last March 30, first November 10

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 12May 5May 1Apr 27Apr 24Apr 21Apr 18Apr 14Apr 8
32°FApr 24Apr 19Apr 15Apr 12Apr 9Apr 6Apr 4Apr 1Mar 27
28°FApr 12Apr 7Apr 3Apr 1Mar 30Mar 27Mar 23Mar 19Mar 14
24°FMar 31Mar 28Mar 24Mar 20Mar 18Mar 15Mar 11Mar 7Mar 1
20°FMar 21Mar 18Mar 14Mar 11Mar 7Mar 3Feb 28Feb 24Feb 17
16°FMar 16Mar 8Mar 3Feb 28Feb 25Feb 19Feb 14Feb 7Jan 31

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 5Oct 10Oct 12Oct 15Oct 19Oct 21Oct 24Oct 28Nov 1
32°FOct 14Oct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
28°FOct 27Nov 1Nov 4Nov 7Nov 10Nov 12Nov 15Nov 19Nov 25
24°FNov 8Nov 13Nov 16Nov 20Nov 23Nov 28Dec 1Dec 5Dec 11
20°FNov 19Nov 28Dec 1Dec 4Dec 7Dec 11Dec 17Dec 22Dec 30
16°FDec 3Dec 9Dec 16Dec 21Dec 26Dec 30Jan 2Jan 9Jan 17

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F198192187182178174169164156
32°F222215211207203199195190182
28°F245239234229225221218213207
24°F274265259254250246242236229
20°F301293287281276271266260251
16°F328319312306301297292286276

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
4,546
Cooling degree days, base 65°F
1,284
Growing degree days, base 40°F
6,497
Growing degree days, base 45°F
5,150
Growing degree days, base 50°F
3,960
Growing degree days, base 55°F
2,920
Growing degree days, base 60°F
2,030

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January95209
February80209
March661249
April32323198
May11690440
June15258693
July0392857
August1335800
September37159572
October26523247
November549266
December825019

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 18.6 km from Brandywine. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00189070 (Upper Marlboro 3 Nnw). Public domain.