Schoolcraft County climate

Schoolcraft County Frost Dates and Growing Season

NOAA 1991-2020 normals for Manistique Wwtp, 11.7 km from Schoolcraft County, elevation 600 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Manistique Wwtp. 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 9 and the first fall freeze around October 10, a growing season of about 154 days.

Median at 36°F
last May 22, first October 1
Median at 32°F
last May 9, first October 10
Median at 28°F
last April 27, first October 26

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 4May 31May 28May 25May 22May 20May 17May 13May 8
32°FMay 23May 19May 15May 12May 9May 6May 3Apr 30Apr 27
28°FMay 10May 5May 2Apr 30Apr 27Apr 24Apr 20Apr 16Apr 11
24°FApr 28Apr 23Apr 19Apr 17Apr 15Apr 11Apr 9Apr 5Apr 1
20°FApr 19Apr 15Apr 11Apr 8Apr 5Apr 3Mar 31Mar 29Mar 22
16°FApr 11Apr 6Apr 4Apr 2Mar 31Mar 28Mar 24Mar 20Mar 15

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 15Sep 21Sep 25Sep 28Oct 1Oct 2Oct 5Oct 8Oct 12
32°FSep 27Oct 2Oct 5Oct 8Oct 10Oct 13Oct 17Oct 21Oct 27
28°FOct 9Oct 13Oct 19Oct 23Oct 26Oct 30Nov 1Nov 4Nov 11
24°FOct 25Oct 30Nov 1Nov 4Nov 7Nov 10Nov 14Nov 17Nov 22
20°FNov 4Nov 8Nov 12Nov 15Nov 18Nov 20Nov 23Nov 27Dec 1
16°FNov 11Nov 17Nov 20Nov 24Nov 27Nov 29Dec 1Dec 5Dec 11

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°F149142138133130126122117111
32°F174167163158154150146141135
28°F201194190185181176172167160
24°F224219214210206203199194187
20°F244238233229226223218213208
16°F262254248244241237233229221

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
8,560
Cooling degree days, base 65°F
145
Growing degree days, base 40°F
3,234
Growing degree days, base 45°F
2,329
Growing degree days, base 50°F
1,560
Growing degree days, base 55°F
929
Growing degree days, base 60°F
447

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,46500
February1,28800
March1,18300
April82103
May497166
June18912278
July6659459
August6258460
September23315249
October591045
November91401
December1,25400

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 11.7 km from Schoolcraft 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 USC00205073 (Manistique Wwtp). Public domain.