Plummer climate

Plummer Frost Dates and Growing Season

NOAA 1991-2020 normals for Plummer 3 Wsw, 5.7 km from Plummer, elevation 2905 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Plummer 3 Wsw. 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 11 and the first fall freeze around October 5, a growing season of about 143 days.

Median at 36°F
last June 7, first September 20
Median at 32°F
last May 11, first October 5
Median at 28°F
last April 22, first October 19

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 24Jun 18Jun 14Jun 11Jun 7Jun 3May 30May 24May 15
32°FJun 4May 28May 21May 15May 11May 7May 3Apr 30Apr 25
28°FMay 10May 3Apr 29Apr 25Apr 22Apr 17Apr 12Apr 6Mar 29
24°FApr 19Apr 9Apr 2Mar 29Mar 24Mar 20Mar 15Mar 10Mar 5
20°FMar 25Mar 17Mar 13Mar 9Mar 6Mar 3Mar 1Feb 24Feb 15
16°FMar 15Mar 8Mar 3Feb 28Feb 25Feb 20Feb 14Feb 5Jan 25

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°FAug 25Sep 4Sep 10Sep 15Sep 20Sep 24Sep 29Oct 2Oct 7
32°FSep 15Sep 24Sep 29Oct 2Oct 5Oct 8Oct 12Oct 16Oct 21
28°FOct 2Oct 8Oct 12Oct 15Oct 19Oct 22Oct 25Oct 30Nov 6
24°FOct 15Oct 20Oct 25Oct 28Nov 1Nov 6Nov 11Nov 16Nov 23
20°FOct 25Nov 1Nov 8Nov 13Nov 19Nov 22Nov 27Nov 30Dec 6
16°FNov 5Nov 15Nov 23Nov 27Dec 1Dec 4Dec 8Dec 13Dec 26

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°F13212011410910398918474
32°F169161155150143137130122111
28°F207198192186181175170163153
24°F248240233228223217211202192
20°F282273266260254249242236224
16°F314301292285280274268260250

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
7,000
Cooling degree days, base 65°F
278
Growing degree days, base 40°F
3,623
Growing degree days, base 45°F
2,585
Growing degree days, base 50°F
1,748
Growing degree days, base 55°F
1,089
Growing degree days, base 60°F
601

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07900
February91700
March83702
April613026
May3883135
June25015229
July69117514
August63117520
September22426266
October574154
November86104
December1,12500

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 5.7 km from Plummer. 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 USC00107188 (Plummer 3 Wsw). Public domain.