Colfax climate

Colfax Frost Dates and Growing Season

NOAA 1991-2020 normals for Colfax, 1.2 km from Colfax, elevation 2380 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Colfax. 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 3 and the first fall freeze around November 24, a growing season of about 233 days.

Median at 36°F
last April 23, first November 7
Median at 32°F
last April 3, first November 24
Median at 28°F
last February 21, first December 13

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 17May 7Apr 30Apr 27Apr 23Apr 19Apr 15Apr 11Apr 3
32°FApr 29Apr 19Apr 13Apr 8Apr 3Mar 29Mar 21Mar 14Feb 28
28°FApr 6Mar 25Mar 9Feb 28Feb 21Feb 13Feb 3Jan 21Jan 5
24°FFeb 17Feb 4Jan 27Jan 18Jan 9Jan 4Dec 31Dec 21Dec 10
20°F–––––––––
16°F–––––––––

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 18Oct 25Oct 31Nov 4Nov 7Nov 11Nov 15Nov 18Nov 24
32°FNov 2Nov 11Nov 16Nov 20Nov 24Nov 28Dec 1Dec 5Dec 11
28°FNov 21Nov 29Dec 3Dec 8Dec 13Dec 17Dec 24Jan 1Jan 14
24°FDec 1Dec 13Dec 20Dec 27Jan 1Jan 5Jan 13Jan 24Feb 9
20°F–––––––––
16°F–––––––––

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°F223214207201196190184176167
32°F270258247240233225218211198
28°F343329316304294283273260245
24°F365365365365361353343333315
20°F365365365365365365365365363
16°F365365365365365365365365365

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
98% of years
24°F or colder
51% of years
20°F or colder
10% of years
16°F or colder
0% 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
3,335
Cooling degree days, base 65°F
1,273
Growing degree days, base 40°F
7,128
Growing degree days, base 45°F
5,501
Growing degree days, base 50°F
4,102
Growing degree days, base 55°F
2,956
Growing degree days, base 60°F
2,025

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January595033
February500045
March469189
April3348166
May16157369
June43185593
July2383846
August2351814
September24227653
October15660377
November4242100
December626017

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 Colfax. 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 USC00041912 (Colfax). Public domain.