Leesburg climate

Leesburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Leesburg 2, 3.8 km from Leesburg, elevation 260 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Leesburg 2. 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 March 12 and the first fall freeze around November 19, a growing season of about 253 days.

Median at 36°F
last March 24, first November 8
Median at 32°F
last March 12, first November 19
Median at 28°F
last February 26, first December 4

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°FApr 10Apr 5Apr 1Mar 28Mar 24Mar 20Mar 16Mar 11Mar 3
32°FMar 30Mar 24Mar 19Mar 16Mar 12Mar 7Mar 3Feb 28Feb 18
28°FMar 18Mar 11Mar 6Mar 1Feb 26Feb 20Feb 11Feb 4Jan 28
24°FMar 8Feb 28Feb 20Feb 11Feb 4Jan 31Jan 26Jan 17Jan 4
20°FFeb 25Feb 10Feb 3Jan 30Jan 23Jan 17Jan 11Jan 4Dec 25
16°FFeb 5Jan 31Jan 26Jan 21Jan 17Jan 12Jan 7Jan 1Dec 22

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 25Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 25
32°FNov 3Nov 9Nov 12Nov 16Nov 19Nov 23Nov 27Dec 3Dec 11
28°FNov 12Nov 18Nov 24Nov 30Dec 4Dec 9Dec 18Dec 27Jan 5
24°FNov 26Dec 4Dec 10Dec 19Dec 27Jan 1Jan 7Jan 15Jan 28
20°FDec 8Dec 17Dec 26Jan 1Jan 7Jan 12Jan 17Jan 26Feb 6
16°FDec 16Dec 28Jan 2Jan 7Jan 11Jan 17Jan 21Jan 27Feb 1

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°F254244238233228223219214206
32°F282271263258253247242235227
28°F320307299291284276269263253
24°F358342334328320310303294280
20°F365365365362353343334325311
16°F365365365365365365365358338

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
93% of years
20°F or colder
62% of years
16°F or colder
22% 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
2,024
Cooling degree days, base 65°F
2,338
Growing degree days, base 40°F
9,495
Growing degree days, base 45°F
7,777
Growing degree days, base 50°F
6,185
Growing degree days, base 55°F
4,737
Growing degree days, base 60°F
3,444

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January523499
February3814118
March24123273
April8481449
May11267721
June0424874
July0518983
August0504969
September1354802
October66133533
November26522235
December4526129

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 3.8 km from Leesburg. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00095061 (Leesburg 2). Public domain.