Golden climate

Golden Frost Dates and Growing Season

NOAA 1991-2020 normals for Golden, 0.5 km from Golden, elevation 718 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Golden. 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 April 18 and the first fall freeze around October 21, a growing season of about 187 days.

Median at 36°F
last April 28, first October 11
Median at 32°F
last April 18, first October 21
Median at 28°F
last April 7, first October 31

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 11May 5May 2Apr 30Apr 28Apr 24Apr 22Apr 18Apr 13
32°FMay 1Apr 26Apr 23Apr 20Apr 18Apr 14Apr 11Apr 7Apr 3
28°FApr 21Apr 17Apr 13Apr 10Apr 7Apr 4Apr 1Mar 29Mar 21
24°FApr 12Apr 7Apr 3Apr 1Mar 29Mar 25Mar 20Mar 16Mar 10
20°FApr 3Mar 30Mar 25Mar 21Mar 17Mar 14Mar 10Mar 7Mar 1
16°FMar 25Mar 19Mar 16Mar 12Mar 9Mar 6Mar 3Feb 28Feb 21

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 25Sep 30Oct 4Oct 8Oct 11Oct 14Oct 16Oct 19Oct 23
32°FOct 6Oct 12Oct 15Oct 19Oct 21Oct 23Oct 25Oct 29Nov 1
28°FOct 19Oct 23Oct 26Oct 29Oct 31Nov 2Nov 5Nov 9Nov 14
24°FOct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 20Nov 25
20°FNov 6Nov 11Nov 14Nov 18Nov 21Nov 24Nov 27Dec 1Dec 7
16°FNov 13Nov 18Nov 22Nov 26Nov 29Dec 3Dec 7Dec 12Dec 18

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°F184178173170166162158153147
32°F204199194191187183178173166
28°F227220215211207203199193187
24°F251244237233228225221215208
20°F272264257252248245239235226
16°F290282277272267262257252245

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
5,781
Cooling degree days, base 65°F
1,077
Growing degree days, base 40°F
5,810
Growing degree days, base 45°F
4,610
Growing degree days, base 50°F
3,540
Growing degree days, base 55°F
2,590
Growing degree days, base 60°F
1,764

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24001
February1,00102
March763041
April4119142
May13878409
June12242679
July1329794
August5275735
September84127496
October34617197
November707038
December1,07405

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 0.5 km from Golden. 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 USC00113530 (Golden). Public domain.