Converse County climate

Converse County Frost Dates and Growing Season

NOAA 1991-2020 normals for Douglas Converse CO AP, 21.8 km from Converse County, elevation 4929 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Douglas Converse CO AP. 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 23 and the first fall freeze around September 22, a growing season of about 122 days.

Median at 36°F
last June 5, first September 12
Median at 32°F
last May 23, first September 22
Median at 28°F
last May 8, first October 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°FJun 18Jun 14Jun 10Jun 7Jun 5Jun 2May 31May 26May 22
32°FJun 7Jun 1May 29May 25May 23May 19May 16May 13May 10
28°FMay 24May 17May 13May 11May 8May 6May 4May 1Apr 28
24°FMay 11May 6May 3Apr 30Apr 28Apr 25Apr 21Apr 18Apr 12
20°FMay 2Apr 28Apr 23Apr 19Apr 15Apr 12Apr 8Apr 4Mar 29
16°FApr 21Apr 15Apr 9Apr 5Apr 3Mar 31Mar 26Mar 20Mar 12

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 30Sep 4Sep 7Sep 10Sep 12Sep 15Sep 18Sep 21Sep 25
32°FSep 9Sep 13Sep 16Sep 19Sep 22Sep 25Sep 27Sep 30Oct 4
28°FSep 17Sep 22Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
24°FSep 27Oct 1Oct 5Oct 9Oct 12Oct 15Oct 17Oct 20Oct 24
20°FOct 5Oct 12Oct 15Oct 18Oct 21Oct 23Oct 26Oct 29Nov 1
16°FOct 14Oct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 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°F1201131081039995928781
32°F140134129125122118114109102
28°F162156152148144141136131124
24°F184178173168165160156152146
20°F210201196191186182178173166
16°F231224216211206202198193183

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
7,303
Cooling degree days, base 65°F
512
Growing degree days, base 40°F
4,188
Growing degree days, base 45°F
3,157
Growing degree days, base 50°F
2,282
Growing degree days, base 55°F
1,556
Growing degree days, base 60°F
969

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21500
February1,06101
March884010
April644029
May3837158
June10767412
July11225678
August27178617
September19735310
October602060
November93006
December1,24300

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 21.8 km from Converse 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 USW00094057 (Douglas Converse CO AP). Public domain.