Warm Springs climate

Warm Springs Frost Dates and Growing Season

NOAA 1991-2020 normals for Pelton Dam, 4.1 km from Warm Springs, elevation 1410 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pelton Dam. 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 5 and the first fall freeze around October 7, a growing season of about 154 days.

Median at 36°F
last May 28, first September 26
Median at 32°F
last May 5, first October 7
Median at 28°F
last April 20, first October 20

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 20Jun 12Jun 6Jun 1May 28May 24May 18May 14May 8
32°FMay 29May 18May 13May 9May 5May 2Apr 30Apr 27Apr 21
28°FMay 7May 2Apr 28Apr 24Apr 20Apr 16Apr 11Apr 6Mar 30
24°FApr 21Apr 12Apr 5Mar 31Mar 28Mar 21Mar 14Mar 7Feb 27
20°FMar 29Mar 17Mar 10Mar 3Feb 28Feb 25Feb 20Feb 13Feb 1
16°FMar 6Feb 28Feb 23Feb 17Feb 11Feb 2Jan 25Jan 12Dec 27

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 7Sep 12Sep 18Sep 22Sep 26Sep 28Oct 1Oct 3Oct 8
32°FSep 24Oct 1Oct 3Oct 5Oct 7Oct 10Oct 13Oct 17Oct 22
28°FOct 4Oct 9Oct 13Oct 17Oct 20Oct 22Oct 26Oct 30Nov 4
24°FOct 17Oct 22Oct 26Oct 30Nov 2Nov 6Nov 11Nov 17Nov 27
20°FOct 24Nov 1Nov 6Nov 12Nov 18Nov 23Nov 29Dec 5Dec 18
16°FNov 5Nov 13Nov 22Nov 28Dec 3Dec 8Dec 16Dec 25Jan 9

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°F1451361291241191131079990
32°F175167162157154149144137128
28°F208199193187182177172165157
24°F253243233227219213207199189
20°F302286277269263256248239228
16°F345329318309302294285274261

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
97% 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
5,325
Cooling degree days, base 65°F
649
Growing degree days, base 40°F
5,058
Growing degree days, base 45°F
3,778
Growing degree days, base 50°F
2,721
Growing degree days, base 55°F
1,865
Growing degree days, base 60°F
1,177

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January92502
February74503
March646015
April466174
May24124261
June9578434
July14246697
August13224676
September10372421
October4083122
November719013
December95002

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 4.1 km from Warm Springs. 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 USC00356532 (Pelton Dam). Public domain.