Central City climate

Central City Frost Dates and Growing Season

NOAA 1991-2020 normals for Coal Creek Canyon, 15.2 km from Central City, elevation 8951 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Coal Creek Canyon. 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 June 5 and the first fall freeze around September 16, a growing season of about 103 days.

Median at 36°F
last June 19, first September 4
Median at 32°F
last June 5, first September 16
Median at 28°F
last May 21, first September 26

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

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 18Aug 26Aug 30Sep 1Sep 4Sep 7Sep 10Sep 13Sep 17
32°FSep 2Sep 7Sep 10Sep 13Sep 16Sep 19Sep 22Sep 24Sep 28
28°FSep 11Sep 17Sep 21Sep 24Sep 26Sep 28Oct 1Oct 5Oct 10
24°FSep 21Sep 26Sep 29Oct 2Oct 5Oct 8Oct 11Oct 14Oct 20
20°FSep 28Oct 3Oct 7Oct 10Oct 13Oct 16Oct 20Oct 24Oct 31
16°FOct 6Oct 11Oct 15Oct 19Oct 23Oct 27Oct 31Nov 3Nov 9

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°F979085807672676153
32°F12211511010710399959083
28°F144139134130126122117111104
24°F167159154150147142138133125
20°F188179173169165160156150144
16°F208199193188183178173168160

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
9,135
Cooling degree days, base 65°F
19
Growing degree days, base 40°F
2,392
Growing degree days, base 45°F
1,569
Growing degree days, base 50°F
917
Growing degree days, base 55°F
431
Growing degree days, base 60°F
131

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25600
February1,13500
March1,06300
April89602
May653029
June3342155
July15912320
August2014274
September3980120
October750016
November1,02001
December1,27100

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 15.2 km from Central City. 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 USC00051681 (Coal Creek Canyon). Public domain.