Greeley climate

Greeley Frost Dates and Growing Season

NOAA 1991-2020 normals for Greeley, 0.4 km from Greeley, elevation 2020 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Greeley. 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 5 and the first fall freeze around October 2, a growing season of about 149 days.

Median at 36°F
last May 16, first September 23
Median at 32°F
last May 5, first October 2
Median at 28°F
last April 25, first October 11

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

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 9Sep 15Sep 18Sep 21Sep 23Sep 26Sep 29Oct 1Oct 5
32°FSep 19Sep 24Sep 27Sep 30Oct 2Oct 4Oct 7Oct 10Oct 14
28°FSep 28Oct 1Oct 4Oct 7Oct 11Oct 14Oct 17Oct 19Oct 22
24°FOct 4Oct 12Oct 15Oct 18Oct 21Oct 23Oct 25Oct 28Nov 1
20°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11
16°FOct 23Oct 28Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 23

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°F149143139135131127123118113
32°F167160156152149145142137130
28°F187180175171167163160155148
24°F207201196192187183179173166
20°F225218213209205202198193186
16°F245238232228223218213208201

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
6,897
Cooling degree days, base 65°F
770
Growing degree days, base 40°F
4,909
Growing degree days, base 45°F
3,818
Growing degree days, base 50°F
2,861
Growing degree days, base 55°F
2,033
Growing degree days, base 60°F
1,335

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,32400
February1,09501
March884018
April546378
May25636274
June44158564
July7279738
August16214663
September14374391
October4845119
November876014
December1,22300

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 0.4 km from Greeley. 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 USC00253425 (Greeley). Public domain.