Montezuma climate

Montezuma Frost Dates and Growing Season

NOAA 1991-2020 normals for Montezuma, 0.6 km from Montezuma, elevation 2770 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Montezuma. 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 23 and the first fall freeze around October 20, a growing season of about 177 days.

Median at 36°F
last May 3, first October 9
Median at 32°F
last April 23, first October 20
Median at 28°F
last April 14, first October 27

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 15May 11May 7May 5May 3Apr 30Apr 28Apr 24Apr 20
32°FMay 6May 2Apr 30Apr 26Apr 23Apr 21Apr 18Apr 15Apr 10
28°FApr 28Apr 23Apr 20Apr 18Apr 14Apr 12Apr 8Apr 5Mar 31
24°FApr 20Apr 14Apr 11Apr 7Apr 4Apr 1Mar 28Mar 23Mar 15
20°FApr 10Apr 5Apr 1Mar 28Mar 23Mar 18Mar 12Mar 8Mar 2
16°FMar 31Mar 23Mar 18Mar 13Mar 9Mar 5Mar 2Feb 27Feb 20

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 26Oct 1Oct 4Oct 6Oct 9Oct 12Oct 15Oct 18Oct 22
32°FOct 5Oct 11Oct 14Oct 17Oct 20Oct 22Oct 25Oct 27Oct 31
28°FOct 15Oct 20Oct 22Oct 25Oct 27Oct 30Nov 1Nov 4Nov 9
24°FOct 22Oct 27Oct 31Nov 2Nov 5Nov 7Nov 10Nov 14Nov 19
20°FOct 29Nov 3Nov 7Nov 10Nov 13Nov 16Nov 19Nov 22Nov 28
16°FNov 5Nov 10Nov 15Nov 18Nov 22Nov 26Nov 29Dec 3Dec 10

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°F176170166163159155151147140
32°F196189185181177174170165157
28°F216210204200196193188184176
24°F236228224220215211207202194
20°F259251246240235230226220212
16°F280271266260255250245238230

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
4,980
Cooling degree days, base 65°F
1,362
Growing degree days, base 40°F
6,392
Growing degree days, base 45°F
5,092
Growing degree days, base 50°F
3,947
Growing degree days, base 55°F
2,952
Growing degree days, base 60°F
2,092

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00802
February822010
March636261
April37011170
May13487426
June12273711
July1434897
August3361823
September55168565
October30727239
November656142
December97803

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 0.6 km from Montezuma. 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 USC00145421 (Montezuma). Public domain.