Grace climate

Grace Frost Dates and Growing Season

NOAA 1991-2020 normals for Grace, 1.3 km from Grace, elevation 5550 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grace. 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 29 and the first fall freeze around September 17, a growing season of about 111 days.

Median at 36°F
last June 16, first September 4
Median at 32°F
last May 29, first September 17
Median at 28°F
last May 9, first October 1

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°FJul 5Jun 28Jun 24Jun 20Jun 16Jun 13Jun 9Jun 4May 29
32°FJun 16Jun 11Jun 5Jun 1May 29May 25May 21May 17May 11
28°FMay 25May 20May 15May 12May 9May 7May 3Apr 30Apr 27
24°FMay 9May 4Apr 30Apr 28Apr 25Apr 22Apr 19Apr 14Apr 9
20°FApr 26Apr 19Apr 15Apr 12Apr 8Apr 6Apr 2Mar 30Mar 23
16°FApr 11Apr 6Apr 3Mar 31Mar 27Mar 23Mar 19Mar 14Mar 8

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°FAug 22Aug 27Aug 31Sep 2Sep 4Sep 7Sep 10Sep 14Sep 19
32°FSep 1Sep 6Sep 10Sep 14Sep 17Sep 21Sep 24Sep 27Oct 1
28°FSep 15Sep 21Sep 25Sep 28Oct 1Oct 3Oct 7Oct 11Oct 16
24°FSep 28Oct 2Oct 5Oct 10Oct 13Oct 16Oct 19Oct 22Oct 28
20°FOct 9Oct 15Oct 19Oct 22Oct 25Oct 29Nov 1Nov 5Nov 10
16°FOct 20Oct 25Oct 29Nov 1Nov 4Nov 8Nov 11Nov 16Nov 21

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°F1029488837873686353
32°F1361261201151111061009486
28°F165158153148143139134129121
24°F192185180176171167162157149
20°F219212206202198194188183175
16°F246237231227221216212206199

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
7,955
Cooling degree days, base 65°F
238
Growing degree days, base 40°F
3,500
Growing degree days, base 45°F
2,546
Growing degree days, base 50°F
1,749
Growing degree days, base 55°F
1,099
Growing degree days, base 60°F
589

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33600
February1,11900
March96701
April684018
May4411107
June19420289
July35117547
August4989506
September24610240
October614041
November96801
December1,30200

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 1.3 km from Grace. 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 USC00103732 (Grace). Public domain.