Saint Maries climate

Saint Maries Frost Dates and Growing Season

NOAA 1991-2020 normals for Saint Maries, 1.2 km from Saint Maries, elevation 2151 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Saint Maries. 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 3 and the first fall freeze around October 4, a growing season of about 152 days.

Median at 36°F
last May 20, first September 20
Median at 32°F
last May 3, first October 4
Median at 28°F
last April 14, first October 19

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

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 5Sep 10Sep 13Sep 17Sep 20Sep 22Sep 25Sep 29Oct 4
32°FSep 18Sep 24Sep 27Oct 1Oct 4Oct 6Oct 10Oct 14Oct 20
28°FOct 2Oct 7Oct 11Oct 15Oct 19Oct 22Oct 27Nov 1Nov 6
24°FOct 14Oct 21Oct 27Oct 31Nov 3Nov 7Nov 11Nov 17Nov 23
20°FOct 27Nov 1Nov 8Nov 13Nov 18Nov 22Nov 25Dec 1Dec 7
16°FNov 4Nov 13Nov 21Nov 25Dec 1Dec 4Dec 9Dec 17Dec 27

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°F14013312812311911411010495
32°F174166161156152148144139131
28°F213205197193188182176170162
24°F252243237232226221216209200
20°F287276268262257250245239230
16°F317304296288281274267258248

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
6,553
Cooling degree days, base 65°F
331
Growing degree days, base 40°F
3,962
Growing degree days, base 45°F
2,884
Growing degree days, base 50°F
1,995
Growing degree days, base 55°F
1,271
Growing degree days, base 60°F
717

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07100
February88600
March78902
April557039
May3218184
June16133325
July40139564
August42128550
September20023281
October554047
November85102
December1,08200

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 1.2 km from Saint Maries. 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 USC00108062 (Saint Maries). Public domain.