Casco climate

Casco Frost Dates and Growing Season

NOAA 1991-2020 normals for Kewaunee, 13.9 km from Casco, elevation 593 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Kewaunee. 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 1 and the first fall freeze around October 18, a growing season of about 168 days.

Median at 36°F
last May 13, first October 6
Median at 32°F
last May 1, first October 18
Median at 28°F
last April 18, 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 27May 23May 19May 16May 13May 10May 7May 4Apr 29
32°FMay 17May 10May 6May 4May 1Apr 29Apr 25Apr 22Apr 16
28°FMay 3Apr 28Apr 24Apr 21Apr 18Apr 15Apr 12Apr 9Apr 4
24°FApr 19Apr 14Apr 11Apr 8Apr 5Apr 3Apr 1Mar 30Mar 23
20°FApr 8Apr 4Apr 2Mar 31Mar 29Mar 26Mar 23Mar 20Mar 15
16°FApr 3Mar 30Mar 26Mar 23Mar 20Mar 17Mar 15Mar 11Mar 7

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 6Oct 8Oct 11Oct 15Oct 20
32°FOct 2Oct 7Oct 11Oct 15Oct 18Oct 21Oct 25Oct 29Nov 1
28°FOct 15Oct 21Oct 26Oct 28Oct 31Nov 1Nov 4Nov 8Nov 12
24°FOct 29Nov 1Nov 5Nov 8Nov 10Nov 13Nov 15Nov 19Nov 24
20°FNov 7Nov 10Nov 14Nov 17Nov 19Nov 22Nov 25Nov 30Dec 4
16°FNov 13Nov 18Nov 22Nov 25Nov 28Dec 1Dec 4Dec 9Dec 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°F165159154149145140136131126
32°F190183178173168164159153146
28°F214208203199195191187181173
24°F236230226222218214210206200
20°F256249244240236233229226218
16°F274266261256252248244239232

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
7,816
Cooling degree days, base 65°F
324
Growing degree days, base 40°F
3,828
Growing degree days, base 45°F
2,849
Growing degree days, base 50°F
2,010
Growing degree days, base 55°F
1,305
Growing degree days, base 60°F
732

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,41800
February1,22400
March1,07102
April711015
May4094124
June12948371
July31132566
August32111544
September17629311
October523174
November86604
December1,22800

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 13.9 km from Casco. 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 USC00474195 (Kewaunee). Public domain.