Whitefish climate

Whitefish Frost Dates and Growing Season

NOAA 1991-2020 normals for Whitefish, 1.6 km from Whitefish, elevation 3100 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Whitefish. 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 16 and the first fall freeze around September 25, a growing season of about 129 days.

Median at 36°F
last June 7, first September 10
Median at 32°F
last May 16, first September 25
Median at 28°F
last May 1, first October 7

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

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 24Aug 31Sep 4Sep 7Sep 10Sep 13Sep 16Sep 20Sep 24
32°FSep 8Sep 15Sep 19Sep 22Sep 25Sep 27Sep 30Oct 3Oct 8
28°FSep 24Sep 29Oct 2Oct 4Oct 7Oct 11Oct 14Oct 17Oct 21
24°FOct 3Oct 8Oct 13Oct 17Oct 19Oct 23Oct 27Oct 31Nov 5
20°FOct 14Oct 20Oct 25Oct 29Nov 1Nov 4Nov 9Nov 14Nov 21
16°FOct 23Oct 30Nov 3Nov 7Nov 11Nov 16Nov 20Nov 24Dec 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°F116108102979388837666
32°F150143138134129124118111101
28°F178170165161157154150146138
24°F209200195191186182176170163
20°F237230224219215210204197189
16°F263254249243237233229221211

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
8,337
Cooling degree days, base 65°F
173
Growing degree days, base 40°F
3,080
Growing degree days, base 45°F
2,195
Growing degree days, base 50°F
1,456
Growing degree days, base 55°F
866
Growing degree days, base 60°F
442

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,31900
February1,11600
March1,00000
April704012
May4302109
June24214234
July7688478
August9365439
September3214170
October721015
November1,02800
December1,29000

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 1.6 km from Whitefish. 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 USC00248902 (Whitefish). Public domain.