Colfax County climate

Colfax County Frost Dates and Growing Season

NOAA 1991-2020 normals for Maxwell 3 Nw, 6.7 km from Colfax County, elevation 6017 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Maxwell 3 Nw. 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 17 and the first fall freeze around October 1, a growing season of about 135 days.

Median at 36°F
last May 31, first September 24
Median at 32°F
last May 17, first October 1
Median at 28°F
last May 5, first October 8

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 13Jun 7Jun 4Jun 1May 31May 28May 25May 21May 17
32°FMay 31May 26May 22May 20May 17May 14May 11May 8May 4
28°FMay 18May 14May 11May 8May 5May 2Apr 30Apr 27Apr 23
24°FMay 8May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 10
20°FApr 27Apr 23Apr 19Apr 15Apr 12Apr 9Apr 6Apr 3Mar 30
16°FApr 16Apr 9Apr 6Apr 3Apr 1Mar 29Mar 24Mar 18Mar 13

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 13Sep 16Sep 20Sep 22Sep 24Sep 26Sep 28Sep 30Oct 2
32°FSep 20Sep 24Sep 27Sep 29Oct 1Oct 3Oct 5Oct 7Oct 11
28°FSep 26Sep 30Oct 3Oct 5Oct 8Oct 11Oct 14Oct 17Oct 20
24°FOct 3Oct 8Oct 12Oct 15Oct 17Oct 20Oct 22Oct 25Oct 30
20°FOct 12Oct 18Oct 21Oct 23Oct 26Oct 30Nov 1Nov 4Nov 8
16°FOct 20Oct 25Oct 30Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17

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°F13112612211911511210910599
32°F152146142139135132128124118
28°F171166162158155151147143137
24°F191185180176173169166162155
20°F213208204199196190185181174
16°F238230225220215212208203196

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
6,233
Cooling degree days, base 65°F
328
Growing degree days, base 40°F
4,420
Growing degree days, base 45°F
3,277
Growing degree days, base 50°F
2,298
Growing degree days, base 55°F
1,481
Growing degree days, base 60°F
820

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,09600
February91601
March77408
April543044
May2836213
June6360447
July8139597
August15100550
September13522342
October476089
November81206
December1,11400

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 6.7 km from Colfax County. 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 USC00295490 (Maxwell 3 Nw). Public domain.