Hildale climate

Hildale Frost Dates and Growing Season

NOAA 1991-2020 normals for Colorado City, 1.2 km from Hildale, elevation 5001 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Colorado City. 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 26 and the first fall freeze around October 25, a growing season of about 180 days.

Median at 36°F
last May 8, first October 15
Median at 32°F
last April 26, first October 25
Median at 28°F
last April 10, first November 5

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 31May 22May 16May 12May 8May 5May 1Apr 28Apr 23
32°FMay 15May 8May 3Apr 30Apr 26Apr 23Apr 18Apr 13Apr 6
28°FMay 2Apr 25Apr 20Apr 15Apr 10Apr 6Apr 1Mar 27Mar 17
24°FApr 12Apr 4Mar 30Mar 24Mar 17Mar 12Mar 6Mar 1Feb 22
20°FMar 19Mar 10Mar 5Mar 1Feb 25Feb 21Feb 15Feb 10Feb 2
16°FMar 3Feb 23Feb 18Feb 13Feb 7Feb 3Jan 28Jan 20Jan 9

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°FOct 1Oct 6Oct 9Oct 13Oct 15Oct 18Oct 22Oct 25Oct 29
32°FOct 11Oct 16Oct 19Oct 22Oct 25Oct 28Nov 1Nov 4Nov 9
28°FOct 19Oct 25Oct 29Nov 1Nov 5Nov 7Nov 11Nov 14Nov 19
24°FOct 29Nov 4Nov 9Nov 12Nov 15Nov 18Nov 20Nov 24Nov 29
20°FNov 7Nov 14Nov 18Nov 21Nov 24Nov 28Dec 1Dec 5Dec 11
16°FNov 18Nov 24Nov 28Dec 1Dec 4Dec 8Dec 12Dec 18Dec 26

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°F180172167162157152147141134
32°F205197191186180175171166157
28°F234225219213206201195188180
24°F269260253247241234228219210
20°F299290283276270265259253243
16°F332321313305299293287280270

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
4,457
Cooling degree days, base 65°F
1,233
Growing degree days, base 40°F
6,351
Growing degree days, base 45°F
4,984
Growing degree days, base 50°F
3,812
Growing degree days, base 55°F
2,806
Growing degree days, base 60°F
1,949

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January87701
February68707
March566049
April3723142
May15153378
June23228656
July0408872
August1365829
September28158581
October25418257
November603038
December89601

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 1.2 km from Hildale. 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 USC00021920 (Colorado City). Public domain.