Coram climate

Coram Frost Dates and Growing Season

NOAA 1991-2020 normals for W Glacier, 10.2 km from Coram, elevation 3148 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for W Glacier. 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 18 and the first fall freeze around September 20, a growing season of about 124 days.

Median at 36°F
last June 8, first September 4
Median at 32°F
last May 18, first September 20
Median at 28°F
last May 1, first October 4

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°FJul 1Jun 23Jun 16Jun 11Jun 8Jun 4Jun 1May 28May 23
32°FJun 4May 29May 24May 21May 18May 15May 13May 10May 6
28°FMay 15May 10May 7May 4May 1Apr 29Apr 27Apr 23Apr 18
24°FApr 28Apr 24Apr 21Apr 17Apr 14Apr 11Apr 7Apr 4Mar 31
20°FApr 17Apr 11Apr 6Apr 3Mar 31Mar 27Mar 23Mar 19Mar 12
16°FApr 3Mar 30Mar 26Mar 22Mar 18Mar 14Mar 10Mar 7Mar 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 19Aug 25Aug 30Sep 1Sep 4Sep 7Sep 10Sep 15Sep 20
32°FSep 3Sep 9Sep 13Sep 17Sep 20Sep 23Sep 26Sep 30Oct 4
28°FSep 20Sep 26Sep 29Oct 1Oct 4Oct 7Oct 10Oct 15Oct 21
24°FOct 1Oct 6Oct 10Oct 15Oct 19Oct 24Oct 28Nov 1Nov 8
20°FOct 12Oct 19Oct 26Oct 30Nov 2Nov 6Nov 11Nov 16Nov 23
16°FOct 22Oct 30Nov 3Nov 8Nov 12Nov 17Nov 22Nov 27Dec 3

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°F10710093908580756861
32°F142136132128124120114108100
28°F174167162158155151147142135
24°F211203197191186181176170163
20°F241233226220216211205200190
16°F265257250244239234228222213

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
8,080
Cooling degree days, base 65°F
138
Growing degree days, base 40°F
3,095
Growing degree days, base 45°F
2,184
Growing degree days, base 50°F
1,429
Growing degree days, base 55°F
829
Growing degree days, base 60°F
398

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25200
February1,07800
March96700
April690010
May4181110
June22912241
July7370462
August9453425
September3224163
October704018
November99901
December1,25400

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 10.2 km from Coram. 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 USC00248809 (W Glacier). Public domain.