South Haven climate

South Haven Frost Dates and Growing Season

NOAA 1991-2020 normals for S Haven, 0.7 km from South Haven, elevation 590 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for S Haven. 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 17 and the first fall freeze around November 5, a growing season of about 201 days.

Median at 36°F
last April 30, first October 25
Median at 32°F
last April 17, first November 5
Median at 28°F
last April 5, first November 14

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 15May 10May 6May 3Apr 30Apr 27Apr 24Apr 20Apr 15
32°FMay 4Apr 29Apr 23Apr 20Apr 17Apr 14Apr 11Apr 7Apr 3
28°FApr 20Apr 15Apr 11Apr 7Apr 5Apr 2Mar 31Mar 27Mar 22
24°FApr 8Apr 3Mar 31Mar 28Mar 26Mar 23Mar 20Mar 17Mar 12
20°FMar 29Mar 25Mar 22Mar 19Mar 16Mar 13Mar 10Mar 5Feb 28
16°FMar 22Mar 17Mar 14Mar 11Mar 7Mar 3Feb 28Feb 23Feb 12

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°FOct 8Oct 14Oct 19Oct 22Oct 25Oct 28Oct 31Nov 2Nov 7
32°FOct 24Oct 28Nov 1Nov 3Nov 5Nov 7Nov 10Nov 14Nov 19
28°FNov 3Nov 6Nov 9Nov 11Nov 14Nov 17Nov 21Nov 26Dec 2
24°FNov 9Nov 14Nov 18Nov 22Nov 26Nov 30Dec 3Dec 8Dec 15
20°FNov 19Nov 25Nov 29Dec 3Dec 7Dec 11Dec 16Dec 20Dec 26
16°FNov 29Dec 5Dec 10Dec 15Dec 20Dec 23Dec 28Jan 3Jan 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°F197189184180177172168163155
32°F221214209205201197193187179
28°F246239233228224220216211204
24°F270262256251246241237231224
20°F291283278273268262257251244
16°F312303297292287282276271262

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
5,879
Cooling degree days, base 65°F
738
Growing degree days, base 40°F
5,168
Growing degree days, base 45°F
4,004
Growing degree days, base 50°F
2,980
Growing degree days, base 55°F
2,087
Growing degree days, base 60°F
1,337

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,15301
February98401
March857017
April522381
May23737283
June53135533
July5247707
August10213668
September7891464
October32813192
November669030
December98404

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 0.7 km from South Haven. 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 USC00207690 (S Haven). Public domain.