Glendale climate

Glendale Frost Dates and Growing Season

NOAA 1991-2020 normals for Denver Water Dept, 6.9 km from Glendale, elevation 5228 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Denver Water Dept. 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 30 and the first fall freeze around October 12, a growing season of about 165 days.

Median at 36°F
last May 8, first October 4
Median at 32°F
last April 30, first October 12
Median at 28°F
last April 18, first October 21

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 25May 17May 14May 11May 8May 6May 3May 1Apr 27
32°FMay 13May 8May 4May 2Apr 30Apr 27Apr 23Apr 19Apr 15
28°FMay 5Apr 30Apr 26Apr 21Apr 18Apr 15Apr 11Apr 7Apr 1
24°FApr 24Apr 19Apr 13Apr 9Apr 4Apr 1Mar 29Mar 22Mar 13
20°FApr 15Apr 6Apr 1Mar 28Mar 23Mar 18Mar 12Mar 7Mar 2
16°FApr 3Mar 27Mar 21Mar 15Mar 10Mar 5Mar 2Feb 26Feb 19

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

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°F166160155151147144140136128
32°F184178173169165161157152145
28°F206199193189184180176171163
24°F232223217211206200196190182
20°F256247240233228223217211202
16°F277266261255250244238231219

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
5,262
Cooling degree days, base 65°F
1,045
Growing degree days, base 40°F
5,757
Growing degree days, base 45°F
4,486
Growing degree days, base 50°F
3,396
Growing degree days, base 55°F
2,467
Growing degree days, base 60°F
1,686

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January93303
February83005
March659045
April4483115
May21946323
June32199617
July2362824
August6311770
September83118492
October3907168
November698030
December96203

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 6.9 km from Glendale. 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 USC00052223 (Denver Water Dept). Public domain.