Chinle climate

Chinle Frost Dates and Growing Season

NOAA 1991-2020 normals for Canyon De Chelly, 1.2 km from Chinle, elevation 5610 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Canyon De Chelly. 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 6 and the first fall freeze around October 8, a growing season of about 153 days.

Median at 36°F
last May 21, first October 1
Median at 32°F
last May 6, first October 8
Median at 28°F
last April 24, 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 9Jun 3May 30May 25May 21May 18May 14May 10May 3
32°FMay 31May 22May 15May 11May 6May 2Apr 30Apr 26Apr 22
28°FMay 12May 4Apr 30Apr 27Apr 24Apr 21Apr 17Apr 13Apr 8
24°FApr 27Apr 21Apr 16Apr 12Apr 9Apr 6Apr 3Mar 30Mar 22
20°FApr 13Apr 6Apr 2Mar 28Mar 23Mar 18Mar 13Mar 9Mar 2
16°FMar 31Mar 18Mar 13Mar 7Mar 3Feb 28Feb 24Feb 17Feb 8

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 20Sep 23Sep 26Sep 29Oct 1Oct 3Oct 6Oct 9Oct 14
32°FSep 26Sep 30Oct 3Oct 5Oct 8Oct 11Oct 15Oct 18Oct 23
28°FOct 1Oct 5Oct 10Oct 15Oct 18Oct 21Oct 24Oct 28Nov 2
24°FOct 11Oct 19Oct 23Oct 26Oct 30Nov 1Nov 4Nov 7Nov 11
20°FOct 23Oct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 17Nov 22
16°FNov 4Nov 9Nov 13Nov 16Nov 19Nov 22Nov 25Nov 29Dec 3

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°F151146140136132128123118110
32°F173167161157153149144138130
28°F198191185180176171166160151
24°F222215210206201196191185177
20°F253246240234229223218213203
16°F287277269264259253247241230

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
5,162
Cooling degree days, base 65°F
985
Growing degree days, base 40°F
5,755
Growing degree days, base 45°F
4,488
Growing degree days, base 50°F
3,391
Growing degree days, base 55°F
2,448
Growing degree days, base 60°F
1,648

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,04200
February78101
March622025
April3811128
May15340359
June15203637
July0358823
August1288752
September5492489
October3533163
November720012
December1,04000

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 Chinle. 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 USC00021248 (Canyon De Chelly). Public domain.