Rolette climate

Rolette Frost Dates and Growing Season

NOAA 1991-2020 normals for Rolette 3SE, 4.3 km from Rolette, elevation 1620 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rolette 3SE. 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 22 and the first fall freeze around September 20, a growing season of about 120 days.

Median at 36°F
last May 30, first September 10
Median at 32°F
last May 22, first September 20
Median at 28°F
last May 13, first September 27

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 14Jun 7Jun 4Jun 1May 30May 28May 25May 23May 19
32°FJun 3May 30May 27May 25May 22May 20May 17May 13May 10
28°FMay 27May 22May 19May 15May 13May 10May 7May 4May 1
24°FMay 16May 12May 8May 5May 3May 1Apr 28Apr 24Apr 19
20°FMay 8May 3May 1Apr 28Apr 24Apr 21Apr 17Apr 13Apr 9
16°FApr 30Apr 25Apr 20Apr 16Apr 13Apr 10Apr 8Apr 5Apr 1

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 24Aug 31Sep 3Sep 6Sep 10Sep 12Sep 15Sep 18Sep 22
32°FSep 5Sep 11Sep 15Sep 17Sep 20Sep 22Sep 24Sep 27Oct 1
28°FSep 17Sep 20Sep 23Sep 25Sep 27Sep 29Oct 1Oct 4Oct 8
24°FSep 24Sep 28Oct 1Oct 3Oct 5Oct 7Oct 10Oct 13Oct 17
20°FOct 1Oct 5Oct 8Oct 11Oct 14Oct 16Oct 19Oct 23Oct 27
16°FOct 9Oct 14Oct 18Oct 21Oct 24Oct 27Oct 30Nov 1Nov 6

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°F12011310910510197928578
32°F138131127124120117113108100
28°F155149145141138134131126121
24°F174167163159155151147142136
20°F193186180177173169164160153
16°F211204200196192188184178171

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
10,714
Cooling degree days, base 65°F
207
Growing degree days, base 40°F
3,204
Growing degree days, base 45°F
2,361
Growing degree days, base 50°F
1,620
Growing degree days, base 55°F
994
Growing degree days, base 60°F
515

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,93900
February1,64100
March1,39400
April828017
May4315132
June14534344
July6189493
August10366429
September32613186
October814021
November1,27500
December1,75800

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 4.3 km from Rolette. 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 USC00327655 (Rolette 3SE). Public domain.