Chippewa County climate

Chippewa County Frost Dates and Growing Season

NOAA 1991-2020 normals for Rudyard 4N, 5 km from Chippewa County, elevation 753 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rudyard 4N. 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 24 and the first fall freeze around October 1, a growing season of about 127 days.

Median at 36°F
last June 6, first September 17
Median at 32°F
last May 24, first October 1
Median at 28°F
last May 8, first October 12

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 30Jun 20Jun 14Jun 10Jun 6Jun 4Jun 1May 29May 24
32°FJun 10Jun 3May 31May 27May 24May 21May 18May 14May 8
28°FMay 26May 21May 16May 12May 8May 5May 2Apr 30Apr 26
24°FMay 11May 4Apr 30Apr 28Apr 26Apr 24Apr 20Apr 17Apr 13
20°FApr 26Apr 21Apr 18Apr 16Apr 14Apr 10Apr 8Apr 4Apr 1
16°FApr 18Apr 14Apr 9Apr 7Apr 4Apr 2Mar 31Mar 29Mar 22

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 1Sep 6Sep 10Sep 13Sep 17Sep 21Sep 24Sep 28Oct 2
32°FSep 14Sep 20Sep 24Sep 27Oct 1Oct 3Oct 5Oct 9Oct 14
28°FSep 27Oct 1Oct 5Oct 8Oct 12Oct 15Oct 19Oct 23Oct 29
24°FOct 9Oct 14Oct 18Oct 23Oct 27Oct 30Nov 1Nov 5Nov 10
20°FOct 24Oct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 24
16°FNov 4Nov 9Nov 13Nov 17Nov 19Nov 23Nov 27Nov 30Dec 4

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°F1211151091049994898271
32°F149142135131127122118113104
28°F176168163158154149144139131
24°F204197191186182177173168160
20°F229222217213208204200194186
16°F248241237232229224220214206

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
8,372
Cooling degree days, base 65°F
231
Growing degree days, base 40°F
3,511
Growing degree days, base 45°F
2,580
Growing degree days, base 50°F
1,783
Growing degree days, base 55°F
1,113
Growing degree days, base 60°F
586

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,49600
February1,29400
March1,14900
April743016
May4007142
June13945359
July5586496
August6675474
September24017247
October607147
November92202
December1,26300

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 km from Chippewa County. 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 USC00207190 (Rudyard 4N). Public domain.