Parmelee climate

Parmelee Frost Dates and Growing Season

NOAA 1991-2020 normals for Harrington, 25.7 km from Parmelee, elevation 2980 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Harrington. 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 1, a growing season of about 143 days.

Median at 36°F
last May 21, first September 23
Median at 32°F
last May 11, first October 1
Median at 28°F
last May 1, first October 10

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 1May 29May 26May 23May 21May 19May 16May 13May 10
32°FMay 24May 19May 16May 13May 11May 8May 5May 2Apr 29
28°FMay 14May 9May 6May 3May 1Apr 29Apr 26Apr 22Apr 17
24°FMay 4Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 11Apr 7
20°FApr 25Apr 20Apr 16Apr 13Apr 10Apr 7Apr 5Apr 1Mar 27
16°FApr 17Apr 12Apr 8Apr 4Apr 1Mar 29Mar 26Mar 21Mar 14

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 10Sep 15Sep 18Sep 21Sep 23Sep 26Sep 29Oct 2Oct 6
32°FSep 18Sep 23Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
28°FSep 26Oct 1Oct 4Oct 7Oct 10Oct 13Oct 15Oct 18Oct 22
24°FOct 3Oct 9Oct 13Oct 16Oct 19Oct 22Oct 24Oct 27Nov 1
20°FOct 12Oct 17Oct 21Oct 24Oct 26Oct 28Nov 1Nov 4Nov 8
16°FOct 20Oct 25Oct 28Oct 31Nov 2Nov 5Nov 9Nov 12Nov 17

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°F143137132128125121118113106
32°F160155150147143140136130124
28°F180173169165161157152148143
24°F199192187183178174171166158
20°F217210205200196192188184177
16°F239231225220215210206201193

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
7,029
Cooling degree days, base 65°F
708
Growing degree days, base 40°F
4,730
Growing degree days, base 45°F
3,653
Growing degree days, base 50°F
2,717
Growing degree days, base 55°F
1,910
Growing degree days, base 60°F
1,238

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,28300
February1,08301
March888017
April588159
May28920234
June68112497
July12266719
August19220667
September13985405
October5214104
November900014
December1,23800

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 25.7 km from Parmelee. 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 USC00393574 (Harrington). Public domain.