Clayton climate

Clayton Frost Dates and Growing Season

NOAA 1991-2020 normals for Clayton 1 N, 1.6 km from Clayton, elevation 5000 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clayton 1 N. 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 May 4 and the first fall freeze around October 11, a growing season of about 159 days.

Median at 36°F
last May 15, first October 3
Median at 32°F
last May 4, first October 11
Median at 28°F
last April 24, first October 20

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 27May 23May 20May 17May 15May 12May 10May 6May 2
32°FMay 19May 14May 10May 7May 4May 1Apr 29Apr 25Apr 21
28°FMay 8May 3Apr 30Apr 27Apr 24Apr 20Apr 18Apr 14Apr 9
24°FApr 26Apr 21Apr 17Apr 14Apr 10Apr 7Apr 4Mar 31Mar 26
20°FApr 14Apr 8Apr 5Apr 2Mar 31Mar 26Mar 22Mar 17Mar 10
16°FApr 2Mar 28Mar 23Mar 18Mar 15Mar 11Mar 7Mar 3Feb 26

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 20Sep 25Sep 28Oct 1Oct 3Oct 5Oct 7Oct 10Oct 15
32°FSep 30Oct 3Oct 6Oct 9Oct 11Oct 14Oct 16Oct 19Oct 22
28°FOct 7Oct 12Oct 16Oct 18Oct 20Oct 22Oct 25Oct 27Nov 1
24°FOct 17Oct 21Oct 24Oct 27Oct 30Nov 1Nov 2Nov 5Nov 9
20°FOct 23Oct 30Nov 2Nov 4Nov 5Nov 8Nov 11Nov 14Nov 18
16°FOct 29Nov 3Nov 6Nov 9Nov 13Nov 17Nov 19Nov 23Nov 28

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°F157152147143140136133129123
32°F177170166163159155151147140
28°F197191185182178174171166159
24°F221214209205201197193187180
20°F243235229225220217213207200
16°F268258253248243238232227218

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
5,037
Cooling degree days, base 65°F
828
Growing degree days, base 40°F
5,688
Growing degree days, base 45°F
4,383
Growing degree days, base 50°F
3,256
Growing degree days, base 55°F
2,291
Growing degree days, base 60°F
1,483

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January95802
February79508
March639040
April3973128
May17242346
June17175607
July2279742
August6235694
September6988471
October3457184
November687028
December95205

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 1.6 km from Clayton. 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 USC00291883 (Clayton 1 N). Public domain.