Seligman climate

Seligman Frost Dates and Growing Season

NOAA 1991-2020 normals for Washburn 5 W, 11.7 km from Seligman, elevation 1400 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Washburn 5 W. 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 4 and the first fall freeze around October 30, a growing season of about 207 days.

Median at 36°F
last April 16, first October 22
Median at 32°F
last April 4, first October 30
Median at 28°F
last March 25, first November 8

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 6Apr 30Apr 25Apr 21Apr 16Apr 12Apr 9Apr 5Mar 31
32°FApr 23Apr 15Apr 10Apr 6Apr 4Mar 31Mar 29Mar 24Mar 18
28°FApr 9Apr 4Mar 31Mar 29Mar 25Mar 22Mar 18Mar 13Mar 6
24°FMar 31Mar 25Mar 21Mar 17Mar 13Mar 10Mar 6Mar 2Feb 24
20°FMar 20Mar 14Mar 10Mar 6Mar 4Feb 28Feb 25Feb 19Feb 11
16°FMar 13Mar 6Mar 3Feb 28Feb 22Feb 18Feb 12Feb 4Jan 26

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 7Oct 13Oct 17Oct 19Oct 22Oct 24Oct 27Oct 31Nov 5
32°FOct 17Oct 21Oct 24Oct 28Oct 30Nov 2Nov 5Nov 9Nov 15
28°FOct 24Oct 30Nov 2Nov 5Nov 8Nov 12Nov 16Nov 21Nov 27
24°FNov 1Nov 7Nov 12Nov 16Nov 20Nov 24Nov 30Dec 3Dec 10
20°FNov 10Nov 17Nov 23Nov 28Dec 1Dec 4Dec 9Dec 14Dec 21
16°FNov 21Nov 28Dec 3Dec 8Dec 13Dec 19Dec 24Dec 31Jan 8

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°F207199195190186180176171162
32°F230222216212207203199194185
28°F254246240235229225220213206
24°F278268262257251246240233225
20°F300291285279273267261255246
16°F327316307302296290283275265

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
4,178
Cooling degree days, base 65°F
1,506
Growing degree days, base 40°F
7,088
Growing degree days, base 45°F
5,672
Growing degree days, base 50°F
4,395
Growing degree days, base 55°F
3,277
Growing degree days, base 60°F
2,316

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January927012
February713032
March551798
April25826259
May95101474
June5291736
July0434899
August1402866
September36199614
October23744300
November523385
December834020

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 11.7 km from Seligman. 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 USC00238740 (Washburn 5 W). Public domain.