Lexington climate

Lexington Frost Dates and Growing Season

NOAA 1991-2020 normals for Lexington 3E, 2.2 km from Lexington, elevation 825 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lexington 3E. 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 8 and the first fall freeze around October 25, a growing season of about 197 days.

Median at 36°F
last April 22, first October 15
Median at 32°F
last April 8, first October 25
Median at 28°F
last March 30, first November 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°FMay 7May 2Apr 29Apr 25Apr 22Apr 18Apr 14Apr 10Apr 6
32°FApr 26Apr 20Apr 14Apr 11Apr 8Apr 5Apr 2Mar 31Mar 24
28°FApr 12Apr 7Apr 4Apr 1Mar 30Mar 26Mar 21Mar 17Mar 10
24°FApr 3Mar 30Mar 25Mar 21Mar 18Mar 15Mar 11Mar 6Mar 1
20°FMar 27Mar 19Mar 16Mar 12Mar 9Mar 5Mar 2Feb 27Feb 20
16°FMar 17Mar 12Mar 8Mar 4Mar 1Feb 27Feb 22Feb 16Feb 10

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°FSep 30Oct 5Oct 9Oct 13Oct 15Oct 18Oct 21Oct 24Oct 27
32°FOct 10Oct 15Oct 19Oct 22Oct 25Oct 27Oct 30Nov 2Nov 7
28°FOct 21Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 13Nov 20
24°FOct 31Nov 3Nov 6Nov 10Nov 13Nov 18Nov 22Nov 27Dec 2
20°FNov 6Nov 12Nov 16Nov 20Nov 25Nov 29Dec 3Dec 7Dec 15
16°FNov 15Nov 23Nov 28Dec 1Dec 5Dec 10Dec 15Dec 20Dec 25

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°F195187183178174170166160153
32°F217211205201197192188183175
28°F242234228224219214210204197
24°F264256250245240236230224215
20°F286276269265259255250242231
16°F303296289284278274268262253

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
4,995
Cooling degree days, base 65°F
1,351
Growing degree days, base 40°F
6,478
Growing degree days, base 45°F
5,185
Growing degree days, base 50°F
4,029
Growing degree days, base 55°F
3,003
Growing degree days, base 60°F
2,110

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11003
February87609
March643369
April33319199
May10792452
June8289732
July0406871
August2354817
September54159557
October28327250
November624262
December95509

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 2.2 km from Lexington. 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 USC00234904 (Lexington 3E). Public domain.