Grant climate

Grant Frost Dates and Growing Season

NOAA 1991-2020 normals for Stillwater 2SW, 6.2 km from Grant, elevation 898 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stillwater 2SW. 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 30 and the first fall freeze around October 11, a growing season of about 163 days.

Median at 36°F
last May 8, first October 2
Median at 32°F
last April 30, first October 11
Median at 28°F
last April 20, first October 23

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 23May 18May 14May 11May 8May 6May 3Apr 30Apr 26
32°FMay 13May 8May 5May 2Apr 30Apr 27Apr 24Apr 21Apr 17
28°FMay 2Apr 28Apr 25Apr 22Apr 20Apr 17Apr 14Apr 11Apr 6
24°FApr 24Apr 20Apr 15Apr 12Apr 9Apr 7Apr 5Apr 2Mar 29
20°FApr 17Apr 10Apr 7Apr 4Apr 2Apr 1Mar 29Mar 24Mar 19
16°FApr 8Apr 4Apr 1Mar 31Mar 27Mar 24Mar 20Mar 17Mar 11

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 24Sep 27Sep 30Oct 2Oct 4Oct 7Oct 10Oct 14
32°FSep 28Oct 2Oct 5Oct 8Oct 11Oct 14Oct 16Oct 20Oct 23
28°FOct 10Oct 13Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
24°FOct 19Oct 24Oct 28Oct 31Nov 1Nov 4Nov 6Nov 10Nov 14
20°FOct 29Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 18Nov 22
16°FNov 4Nov 8Nov 13Nov 15Nov 18Nov 20Nov 23Nov 26Dec 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°F163156152148145141138133127
32°F181175171167163159155150143
28°F203196191188184180176172165
24°F222215211207203200196191184
20°F238231227223220216212208201
16°F254248243239235232228223217

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
8,008
Cooling degree days, base 65°F
511
Growing degree days, base 40°F
4,387
Growing degree days, base 45°F
3,375
Growing degree days, base 50°F
2,473
Growing degree days, base 55°F
1,693
Growing degree days, base 60°F
1,034

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,59200
February1,32300
March1,07408
April616156
May27024246
June4999500
July10190644
August21146590
September16948339
October536484
November95305
December1,39500

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 6.2 km from Grant. 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 USC00218039 (Stillwater 2SW). Public domain.