Garrison climate

Garrison Frost Dates and Growing Season

NOAA 1991-2020 normals for Warnock 2, 18.3 km from Garrison, elevation 910 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Warnock 2. 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 20 and the first fall freeze around October 22, a growing season of about 182 days.

Median at 36°F
last May 2, first October 13
Median at 32°F
last April 20, first October 22
Median at 28°F
last April 5, first November 1

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 14May 10May 6May 2Apr 30Apr 26Apr 23Apr 18
32°FMay 10May 3Apr 27Apr 23Apr 20Apr 17Apr 14Apr 10Apr 5
28°FApr 24Apr 17Apr 12Apr 8Apr 5Apr 2Mar 31Mar 27Mar 21
24°FApr 7Apr 3Mar 31Mar 28Mar 25Mar 22Mar 19Mar 14Mar 7
20°FMar 27Mar 23Mar 19Mar 16Mar 13Mar 10Mar 6Feb 28Feb 21
16°FMar 20Mar 14Mar 10Mar 5Mar 1Feb 26Feb 20Feb 14Feb 5

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 1Oct 5Oct 8Oct 11Oct 13Oct 15Oct 18Oct 20Oct 23
32°FOct 10Oct 14Oct 18Oct 20Oct 22Oct 25Oct 27Oct 30Nov 1
28°FOct 20Oct 24Oct 28Oct 31Nov 1Nov 2Nov 5Nov 9Nov 14
24°FNov 1Nov 3Nov 6Nov 8Nov 12Nov 14Nov 18Nov 23Nov 29
20°FNov 8Nov 13Nov 16Nov 20Nov 24Nov 28Dec 1Dec 6Dec 14
16°FNov 16Nov 24Nov 30Dec 4Dec 9Dec 15Dec 21Dec 27Jan 2

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°F179173169165161157154148142
32°F202196190186182178174168160
28°F226220216211207203198192185
24°F255246241236232228223218211
20°F285275268263258253247241234
16°F312303297290285279273266256

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
4,763
Cooling degree days, base 65°F
966
Growing degree days, base 40°F
6,103
Growing degree days, base 45°F
4,771
Growing degree days, base 50°F
3,596
Growing degree days, base 55°F
2,575
Growing degree days, base 60°F
1,696

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January993010
February812017
March654364
April32416202
May13472408
June14179615
July2290753
August2264727
September56122517
October30518220
November605149
December862015

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 18.3 km from Garrison. 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 USC00158432 (Warnock 2). Public domain.