Lee County climate

Lee County Frost Dates and Growing Season

NOAA 1991-2020 normals for Lexington, 11.5 km from Lee County, elevation 423 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lexington. 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 5 and the first fall freeze around November 21, a growing season of about 262 days.

Median at 36°F
last March 20, first November 10
Median at 32°F
last March 5, first November 21
Median at 28°F
last February 17, first December 3

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 11Apr 4Mar 31Mar 26Mar 20Mar 16Mar 11Mar 5Feb 27
32°FMar 31Mar 21Mar 15Mar 10Mar 5Mar 1Feb 24Feb 19Feb 10
28°FMar 14Mar 7Mar 2Feb 24Feb 17Feb 11Feb 4Jan 30Jan 17
24°FMar 4Feb 22Feb 12Feb 3Jan 30Jan 22Jan 13Jan 4Dec 24
20°FFeb 15Jan 31Jan 22Jan 15Jan 10Jan 4Dec 31Dec 26Dec 14
16°F–––––––––

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 27Nov 1Nov 3Nov 7Nov 10Nov 14Nov 17Nov 22Nov 28
32°FNov 3Nov 7Nov 13Nov 16Nov 21Nov 25Nov 30Dec 3Dec 11
28°FNov 13Nov 20Nov 26Dec 1Dec 3Dec 8Dec 13Dec 23Jan 4
24°FNov 25Dec 1Dec 8Dec 16Dec 24Dec 31Jan 4Jan 11Jan 30
20°FDec 5Dec 15Dec 24Dec 30Jan 1Jan 5Jan 10Jan 16Feb 1
16°F–––––––––

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°F264256248243236230225217209
32°F294282275268262256250243231
28°F331319308301294287278270260
24°F365358348338331322312303289
20°F365365365365365358349339323
16°F365365365365365365365365363

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
89% of years
20°F or colder
47% of years
16°F or colder
10% 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
1,774
Cooling degree days, base 65°F
2,922
Growing degree days, base 40°F
10,327
Growing degree days, base 45°F
8,599
Growing degree days, base 50°F
6,966
Growing degree days, base 55°F
5,464
Growing degree days, base 60°F
4,114

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4778116
February33314168
March19052348
April61133524
May7323781
June0503952
July05971,062
August06111,076
September2425873
October50195611
November22651307
December42813147

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 11.5 km from Lee County. 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 USC00415193 (Lexington). Public domain.