Idamay climate

Idamay Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairmont, 11.3 km from Idamay, elevation 1300 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairmont. 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 18 and the first fall freeze around October 28, a growing season of about 192 days.

Median at 36°F
last April 30, first October 17
Median at 32°F
last April 18, first October 28
Median at 28°F
last April 5, first November 6

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

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°FOct 5Oct 9Oct 12Oct 15Oct 17Oct 20Oct 22Oct 25Oct 29
32°FOct 14Oct 19Oct 22Oct 25Oct 28Oct 31Nov 1Nov 4Nov 8
28°FOct 25Oct 30Nov 2Nov 4Nov 6Nov 9Nov 13Nov 17Nov 24
24°FNov 3Nov 8Nov 11Nov 15Nov 18Nov 22Nov 27Dec 1Dec 7
20°FNov 13Nov 18Nov 23Nov 27Dec 1Dec 5Dec 10Dec 16Dec 25
16°FNov 24Dec 1Dec 7Dec 11Dec 17Dec 22Dec 27Jan 1Jan 8

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°F189182177172167163159154146
32°F214206201196192187180175166
28°F240232227221217212208201194
24°F265257250245240235231224217
20°F291282276271265259254249239
16°F316306300294289284278272262

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
5,017
Cooling degree days, base 65°F
897
Growing degree days, base 40°F
5,904
Growing degree days, base 45°F
4,606
Growing degree days, base 50°F
3,457
Growing degree days, base 55°F
2,454
Growing degree days, base 60°F
1,598

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,029010
February861010
March700256
April35017192
May14668394
June24174600
July2270733
August4238699
September66110495
October32916199
November611154
December894016

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 11.3 km from Idamay. 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 USC00462920 (Fairmont). Public domain.