Bennett climate

Bennett Frost Dates and Growing Season

NOAA 1991-2020 normals for Denver Intl AP, 21.3 km from Bennett, elevation 5414 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Denver Intl 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 5 and the first fall freeze around October 9, a growing season of about 156 days.

Median at 36°F
last May 16, first October 1
Median at 32°F
last May 5, first October 9
Median at 28°F
last April 25, first October 18

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 2May 26May 22May 19May 16May 13May 11May 8May 3
32°FMay 19May 15May 11May 8May 5May 3Apr 30Apr 28Apr 23
28°FMay 9May 4May 1Apr 29Apr 25Apr 23Apr 19Apr 16Apr 10
24°FApr 30Apr 25Apr 22Apr 18Apr 15Apr 11Apr 7Apr 4Mar 31
20°FApr 20Apr 14Apr 9Apr 6Apr 3Mar 31Mar 26Mar 21Mar 13
16°FApr 9Apr 3Mar 30Mar 25Mar 21Mar 16Mar 11Mar 7Mar 1

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 19Sep 23Sep 26Sep 29Oct 1Oct 3Oct 5Oct 9Oct 12
32°FSep 27Oct 1Oct 4Oct 7Oct 9Oct 12Oct 14Oct 17Oct 20
28°FOct 5Oct 10Oct 13Oct 16Oct 18Oct 20Oct 23Oct 27Oct 31
24°FOct 13Oct 16Oct 19Oct 23Oct 26Oct 29Nov 1Nov 4Nov 10
20°FOct 19Oct 24Oct 29Nov 1Nov 4Nov 7Nov 11Nov 15Nov 20
16°FOct 26Nov 1Nov 5Nov 8Nov 12Nov 16Nov 19Nov 23Nov 27

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°F154147143139136132128123117
32°F173168163159156152148143137
28°F194188182178174171166161155
24°F215208202197193189184179173
20°F237229223217212208202196189
16°F259252246240235229223216207

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
5,862
Cooling degree days, base 65°F
850
Growing degree days, base 40°F
5,273
Growing degree days, base 45°F
4,073
Growing degree days, base 50°F
3,044
Growing degree days, base 55°F
2,171
Growing degree days, base 60°F
1,442

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,03402
February90405
March726033
April517179
May26126265
June52147547
July4315776
August9254710
September10599453
October4367147
November767026
December1,04803

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 21.3 km from Bennett. 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 USW00003017 (Denver Intl AP). Public domain.