Stonegate climate

Stonegate Frost Dates and Growing Season

NOAA 1991-2020 normals for Denver Centennial AP, 5.8 km from Stonegate, elevation 5883 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Denver Centennial 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 8, a growing season of about 154 days.

Median at 36°F
last May 15, first October 1
Median at 32°F
last May 5, first October 8
Median at 28°F
last April 25, first October 17

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 30May 24May 21May 18May 15May 12May 10May 7May 3
32°FMay 17May 13May 10May 7May 5May 3Apr 30Apr 28Apr 24
28°FMay 9May 4May 1Apr 28Apr 25Apr 22Apr 19Apr 15Apr 10
24°FApr 30Apr 25Apr 21Apr 17Apr 13Apr 10Apr 6Apr 3Mar 28
20°FApr 22Apr 15Apr 10Apr 6Apr 2Mar 30Mar 25Mar 20Mar 13
16°FApr 13Apr 5Mar 30Mar 25Mar 20Mar 15Mar 11Mar 5Feb 28

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 17Sep 22Sep 25Sep 29Oct 1Oct 3Oct 5Oct 8Oct 12
32°FSep 25Sep 30Oct 3Oct 6Oct 8Oct 11Oct 14Oct 16Oct 20
28°FOct 4Oct 8Oct 12Oct 14Oct 17Oct 19Oct 22Oct 25Oct 28
24°FOct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1Nov 5Nov 10
20°FOct 19Oct 24Oct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 20
16°FOct 25Nov 1Nov 5Nov 9Nov 13Nov 16Nov 20Nov 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°F153147144140136133129124117
32°F170165161157154151147142135
28°F192185180176172168164159153
24°F215208203198194189185180171
20°F238230223218214209204198189
16°F260251244239233228222215207

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
6,014
Cooling degree days, base 65°F
636
Growing degree days, base 40°F
4,888
Growing degree days, base 45°F
3,708
Growing degree days, base 50°F
2,708
Growing degree days, base 55°F
1,871
Growing degree days, base 60°F
1,182

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,02901
February89604
March750024
April548164
May30315223
June63114502
July4251711
August14192643
September12762397
October4683118
November771020
December1,04102

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 5.8 km from Stonegate. 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 USW00093067 (Denver Centennial AP). Public domain.