Divide County climate

Divide County Frost Dates and Growing Season

NOAA 1991-2020 normals for Crosby, 17.7 km from Divide County, elevation 1959 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Crosby. 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 September 23, a growing season of about 128 days.

Median at 36°F
last May 25, first September 15
Median at 32°F
last May 17, first September 23
Median at 28°F
last May 7, first September 30

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

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 2Sep 7Sep 10Sep 13Sep 15Sep 17Sep 19Sep 22Sep 25
32°FSep 11Sep 16Sep 19Sep 21Sep 23Sep 25Sep 27Sep 30Oct 4
28°FSep 19Sep 22Sep 25Sep 28Sep 30Oct 4Oct 7Oct 10Oct 15
24°FSep 25Sep 30Oct 4Oct 7Oct 10Oct 13Oct 16Oct 19Oct 24
20°FOct 5Oct 11Oct 14Oct 17Oct 20Oct 23Oct 26Oct 29Nov 2
16°FOct 13Oct 18Oct 22Oct 25Oct 28Oct 31Nov 2Nov 6Nov 11

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°F1261211171141111071049991
32°F144138134131128125121117110
28°F165157153148145141137133127
24°F184177173169164160156150143
20°F204198193189184180175170163
16°F222214209205201197192187180

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
9,318
Cooling degree days, base 65°F
329
Growing degree days, base 40°F
3,687
Growing degree days, base 45°F
2,766
Growing degree days, base 50°F
1,959
Growing degree days, base 55°F
1,272
Growing degree days, base 60°F
721

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,71300
February1,43200
March1,19402
April704030
May36010176
June11551388
July33129561
August55116526
September26923237
October708138
November1,15801
December1,57800

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 17.7 km from Divide County. 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 USC00321871 (Crosby). Public domain.