Algoma climate

Algoma Frost Dates and Growing Season

NOAA 1991-2020 normals for Forestville-4E, 10.5 km from Algoma, elevation 690 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Forestville-4E. 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 6 and the first fall freeze around October 17, a growing season of about 163 days.

Median at 36°F
last May 19, first October 3
Median at 32°F
last May 6, first October 17
Median at 28°F
last April 23, first November 1

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 2May 28May 25May 22May 19May 16May 13May 11May 6
32°FMay 20May 16May 12May 9May 6May 4May 1Apr 27Apr 22
28°FMay 7May 2Apr 29Apr 26Apr 23Apr 20Apr 17Apr 13Apr 8
24°FApr 23Apr 19Apr 16Apr 13Apr 10Apr 7Apr 5Apr 2Mar 28
20°FApr 13Apr 8Apr 5Apr 3Apr 1Mar 30Mar 27Mar 22Mar 17
16°FApr 5Apr 1Mar 30Mar 26Mar 23Mar 20Mar 17Mar 14Mar 10

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 19Sep 24Sep 28Oct 1Oct 3Oct 6Oct 9Oct 13Oct 18
32°FOct 1Oct 6Oct 10Oct 14Oct 17Oct 21Oct 24Oct 29Nov 2
28°FOct 16Oct 22Oct 27Oct 30Nov 1Nov 2Nov 5Nov 9Nov 13
24°FNov 1Nov 3Nov 6Nov 8Nov 10Nov 13Nov 16Nov 19Nov 24
20°FNov 6Nov 10Nov 14Nov 17Nov 20Nov 22Nov 25Nov 30Dec 5
16°FNov 13Nov 18Nov 22Nov 25Nov 28Dec 1Dec 4Dec 10Dec 16

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°F158151145141137134130125119
32°F183177172167163160155149142
28°F210202198194189186181176169
24°F233227223219215211207202196
20°F251245241236232228224220214
16°F269263258254250245242237230

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
7,871
Cooling degree days, base 65°F
290
Growing degree days, base 40°F
3,806
Growing degree days, base 45°F
2,819
Growing degree days, base 50°F
1,976
Growing degree days, base 55°F
1,265
Growing degree days, base 60°F
693

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,44800
February1,23500
March1,08801
April720013
May4031120
June12536364
July29121556
August30105539
September17726307
October517172
November87003
December1,22900

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 10.5 km from Algoma. 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 USC00472851 (Forestville-4E). Public domain.