Roswell climate

Roswell Frost Dates and Growing Season

NOAA 1991-2020 normals for Roswell Climat, 2.2 km from Roswell, elevation 3605 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Roswell Climat. 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 13 and the first fall freeze around October 30, a growing season of about 197 days.

Median at 36°F
last April 25, first October 21
Median at 32°F
last April 13, first October 30
Median at 28°F
last March 31, 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 7May 3Apr 30Apr 28Apr 25Apr 23Apr 20Apr 17Apr 12
32°FApr 28Apr 24Apr 20Apr 16Apr 13Apr 11Apr 8Apr 4Mar 31
28°FApr 16Apr 9Apr 5Apr 3Mar 31Mar 27Mar 23Mar 18Mar 11
24°FMar 30Mar 24Mar 19Mar 14Mar 11Mar 8Mar 4Feb 28Feb 24
20°FMar 14Mar 8Mar 3Feb 28Feb 25Feb 20Feb 16Feb 10Feb 4
16°FMar 3Feb 24Feb 16Feb 11Feb 6Feb 2Jan 29Jan 22Jan 13

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 8Oct 12Oct 16Oct 19Oct 21Oct 23Oct 26Oct 30Nov 3
32°FOct 16Oct 21Oct 24Oct 28Oct 30Nov 1Nov 4Nov 7Nov 11
28°FOct 25Oct 30Nov 1Nov 4Nov 6Nov 10Nov 12Nov 15Nov 20
24°FNov 1Nov 5Nov 9Nov 13Nov 16Nov 19Nov 22Nov 25Nov 29
20°FNov 8Nov 14Nov 18Nov 22Nov 25Nov 28Dec 2Dec 5Dec 9
16°FNov 17Nov 24Nov 28Dec 2Dec 6Dec 9Dec 13Dec 18Dec 24

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°F195190185181177173169164159
32°F216210204201197193188184177
28°F242234230225221216212206200
24°F269261256251246242238233225
20°F296288282277272266261255246
16°F331320312306299294288280269

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
3,611
Cooling degree days, base 65°F
1,597
Growing degree days, base 40°F
7,424
Growing degree days, base 45°F
5,919
Growing degree days, base 50°F
4,585
Growing degree days, base 55°F
3,421
Growing degree days, base 60°F
2,425

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January79806
February594027
March4142129
April21118271
May59131540
June0367817
July0457922
August1406871
September19183614
October19032321
November531061
December79509

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 2.2 km from Roswell. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00297605 (Roswell Climat). Public domain.