Garrett climate

Garrett Frost Dates and Growing Season

NOAA 1991-2020 normals for Whitman Mission, 4.7 km from Garrett, elevation 632 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Whitman Mission. 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 2 and the first fall freeze around October 1, a growing season of about 151 days.

Median at 36°F
last May 18, first September 17
Median at 32°F
last May 2, first October 1
Median at 28°F
last April 15, first October 12

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 25May 21May 18May 15May 11May 7May 3
32°FMay 18May 13May 8May 5May 2Apr 30Apr 28Apr 24Apr 16
28°FMay 1Apr 27Apr 23Apr 19Apr 15Apr 10Apr 5Mar 31Mar 23
24°FApr 16Apr 7Apr 1Mar 27Mar 20Mar 15Mar 10Mar 5Feb 28
20°FMar 24Mar 13Mar 7Mar 2Feb 28Feb 24Feb 17Feb 7Jan 23
16°FMar 7Feb 28Feb 23Feb 15Feb 7Feb 1Jan 23Jan 10Dec 28

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 1Sep 5Sep 10Sep 14Sep 17Sep 21Sep 24Sep 28Oct 2
32°FSep 14Sep 20Sep 25Sep 28Oct 1Oct 3Oct 5Oct 10Oct 16
28°FSep 28Oct 2Oct 5Oct 8Oct 12Oct 16Oct 20Oct 23Oct 30
24°FOct 7Oct 13Oct 19Oct 24Oct 27Nov 1Nov 5Nov 12Nov 23
20°FOct 21Oct 29Nov 2Nov 8Nov 13Nov 21Nov 27Dec 5Dec 17
16°FNov 1Nov 11Nov 19Nov 26Dec 2Dec 8Dec 16Dec 29Jan 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°F14313513012512111611010393
32°F172164160155151147142136128
28°F208198191186181175171165156
24°F252242234228220213206199189
20°F306291281272263256249239225
16°F349332319311304297286276261

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
96% 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
5,357
Cooling degree days, base 65°F
554
Growing degree days, base 40°F
5,005
Growing degree days, base 45°F
3,701
Growing degree days, base 50°F
2,616
Growing degree days, base 55°F
1,741
Growing degree days, base 60°F
1,054

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January93603
February75704
March629021
April430179
May22320269
June8070440
July12229682
August19195642
September13039361
October449197
November732016
December95904

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 4.7 km from Garrett. 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 USC00459200 (Whitman Mission). Public domain.