Fort Sumner climate

Fort Sumner Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Sumner, 1.3 km from Fort Sumner, elevation 4025 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Sumner. 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 9 and the first fall freeze around October 30, a growing season of about 201 days.

Median at 36°F
last April 22, first October 20
Median at 32°F
last April 9, first October 30
Median at 28°F
last March 26, first November 6

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

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 5Oct 10Oct 15Oct 18Oct 20Oct 23Oct 25Oct 28Nov 1
32°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 3Nov 5Nov 9
28°FOct 24Oct 29Nov 1Nov 4Nov 6Nov 8Nov 11Nov 15Nov 19
24°FOct 31Nov 5Nov 9Nov 13Nov 15Nov 18Nov 21Nov 24Nov 29
20°FNov 8Nov 14Nov 18Nov 21Nov 24Nov 27Nov 30Dec 4Dec 10
16°FNov 17Nov 24Nov 29Dec 2Dec 6Dec 11Dec 15Dec 20Dec 28

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°F197191187183179175172167160
32°F220214209205201197193188180
28°F247238232228224220215210203
24°F270263257253248243238233225
20°F296288280275270266260253244
16°F333319312305299293287279268

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
3,588
Cooling degree days, base 65°F
1,504
Growing degree days, base 40°F
7,360
Growing degree days, base 45°F
5,851
Growing degree days, base 50°F
4,509
Growing degree days, base 55°F
3,342
Growing degree days, base 60°F
2,343

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January783010
February591026
March4243128
April21420279
May56121531
June1343792
July0433897
August0380845
September25181607
October19823307
November515174
December781014

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 1.3 km from Fort Sumner. 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 USC00293294 (Ft Sumner). Public domain.