Georgetown County climate

Georgetown County Frost Dates and Growing Season

NOAA 1991-2020 normals for Georgetown CO AP, 10.9 km from Georgetown County, elevation 30 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Georgetown 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 March 12 and the first fall freeze around November 24, a growing season of about 258 days.

Median at 36°F
last March 25, first November 10
Median at 32°F
last March 12, first November 24
Median at 28°F
last February 25, first December 10

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°FApr 8Apr 3Mar 31Mar 28Mar 25Mar 22Mar 18Mar 14Mar 8
32°FMar 30Mar 24Mar 20Mar 16Mar 12Mar 8Mar 3Feb 25Feb 18
28°FMar 19Mar 12Mar 6Feb 28Feb 25Feb 17Feb 9Feb 2Jan 25
24°FMar 4Feb 26Feb 14Feb 5Jan 31Jan 27Jan 20Jan 12Dec 31
20°FFeb 16Feb 4Jan 31Jan 26Jan 21Jan 16Jan 11Jan 4Dec 29
16°FJan 31Jan 29Jan 23Jan 20Jan 18Jan 14Jan 11Jan 7Jan 2

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 29Nov 1Nov 5Nov 7Nov 10Nov 13Nov 18Nov 22Nov 29
32°FNov 6Nov 11Nov 16Nov 19Nov 24Nov 28Dec 1Dec 7Dec 19
28°FNov 17Nov 24Nov 30Dec 3Dec 10Dec 17Dec 25Jan 1Jan 9
24°FDec 2Dec 11Dec 20Dec 27Jan 1Jan 5Jan 10Jan 17Jan 30
20°FDec 18Dec 27Jan 1Jan 5Jan 10Jan 14Jan 19Jan 24Feb 3
16°FJan 1Jan 4Jan 9Jan 12Jan 14Jan 18Jan 20Jan 25Jan 30

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°F256247242236231228224218211
32°F291280271265258253246239231
28°F329314306301293285278270259
24°F365351341334329320311303292
20°F365365365365364353343335326
16°F365365365365365365365365350

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
99% of years
24°F or colder
89% of years
20°F or colder
52% of years
16°F or colder
18% 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
2,192
Cooling degree days, base 65°F
2,244
Growing degree days, base 40°F
9,255
Growing degree days, base 45°F
7,561
Growing degree days, base 50°F
5,993
Growing degree days, base 55°F
4,571
Growing degree days, base 60°F
3,319

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January537496
February4205107
March30721222
April9882436
May13222674
June0401850
July0521986
August0498962
September2346793
October68119517
November27821223
December4686125

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 10.9 km from Georgetown 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 USC00383470 (Georgetown CO AP). Public domain.