Constantine climate

Constantine Frost Dates and Growing Season

NOAA 1991-2020 normals for Three Rivers, 10.2 km from Constantine, elevation 810 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Three Rivers. 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 April 30 and the first fall freeze around October 17, a growing season of about 170 days.

Median at 36°F
last May 10, first October 5
Median at 32°F
last April 30, first October 17
Median at 28°F
last April 19, first October 31

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°FMay 25May 20May 16May 13May 10May 7May 4Apr 30Apr 25
32°FMay 15May 9May 6May 3Apr 30Apr 27Apr 24Apr 20Apr 16
28°FMay 5Apr 30Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 5
24°FApr 22Apr 17Apr 13Apr 9Apr 6Apr 4Apr 1Mar 30Mar 22
20°FApr 14Apr 6Apr 3Mar 31Mar 29Mar 25Mar 21Mar 18Mar 12
16°FApr 3Mar 30Mar 25Mar 21Mar 17Mar 13Mar 10Mar 6Mar 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°FSep 23Sep 28Oct 1Oct 3Oct 5Oct 7Oct 10Oct 13Oct 17
32°FOct 1Oct 7Oct 11Oct 14Oct 17Oct 20Oct 23Oct 27Nov 1
28°FOct 15Oct 21Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8Nov 13
24°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 21Nov 28
20°FNov 7Nov 12Nov 15Nov 19Nov 23Nov 27Dec 1Dec 4Dec 10
16°FNov 17Nov 23Nov 27Dec 1Dec 4Dec 7Dec 11Dec 16Dec 22

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°F168159155151148145140135129
32°F189182178174170166161156148
28°F211205201197194190185179172
24°F239232226221217213209204198
20°F264254248243239235230225218
16°F286277271266262257252245237

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
6,602
Cooling degree days, base 65°F
615
Growing degree days, base 40°F
4,776
Growing degree days, base 45°F
3,679
Growing degree days, base 50°F
2,716
Growing degree days, base 55°F
1,878
Growing degree days, base 60°F
1,173

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27200
February1,08901
March917017
April544479
May24140288
June48135537
July10209663
August20161606
September13561382
October4495122
November776018
December1,10202

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 10.2 km from Constantine. 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 USC00208184 (Three Rivers). Public domain.