Grant County climate

Grant County Frost Dates and Growing Season

NOAA 1991-2020 normals for Cliff 11 Se, 15.6 km from Grant County, elevation 4773 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cliff 11 Se. 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 9 and the first fall freeze around October 15, a growing season of about 157 days.

Median at 36°F
last May 23, first October 6
Median at 32°F
last May 9, first October 15
Median at 28°F
last April 28, first October 25

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°FJun 7Jun 2May 31May 27May 23May 20May 16May 12May 7
32°FMay 24May 18May 15May 11May 9May 5May 3May 1Apr 28
28°FMay 11May 7May 3May 1Apr 28Apr 25Apr 22Apr 17Apr 12
24°FMay 1Apr 26Apr 21Apr 17Apr 13Apr 9Apr 6Apr 2Mar 29
20°FApr 16Apr 8Apr 3Mar 31Mar 26Mar 22Mar 16Mar 12Mar 4
16°FMar 30Mar 20Mar 12Mar 8Mar 4Feb 28Feb 25Feb 19Feb 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°FSep 25Sep 29Oct 1Oct 4Oct 6Oct 8Oct 10Oct 13Oct 17
32°FOct 3Oct 6Oct 9Oct 12Oct 15Oct 17Oct 19Oct 23Oct 27
28°FOct 9Oct 15Oct 19Oct 22Oct 25Oct 27Oct 30Nov 1Nov 4
24°FOct 21Oct 25Oct 29Nov 1Nov 2Nov 5Nov 7Nov 10Nov 16
20°FOct 29Nov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 22Nov 27
16°FNov 6Nov 12Nov 16Nov 19Nov 22Nov 26Nov 29Dec 3Dec 10

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°F153147143138135131127122115
32°F173168163160157153149144138
28°F196189185180177173170165159
24°F223214210205200196192186180
20°F255246239234228223217211203
16°F293280274268262256250243232

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
4,278
Cooling degree days, base 65°F
875
Growing degree days, base 40°F
5,999
Growing degree days, base 45°F
4,590
Growing degree days, base 50°F
3,393
Growing degree days, base 55°F
2,386
Growing degree days, base 60°F
1,551

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January84200
February65103
March553030
April3551128
May14127354
June11176615
July0304769
August0261725
September29101522
October2615223
November593024
December84300

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 15.6 km from Grant County. 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 USC00291910 (Cliff 11 Se). Public domain.