Clinton County climate

Clinton County Frost Dates and Growing Season

NOAA 1991-2020 normals for WFO Wilmington, 1.4 km from Clinton County, elevation 1053 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for WFO Wilmington. 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 October 22, a growing season of about 187 days.

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

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°F185178173169165161157151144
32°F206200195191187183180174167
28°F231223219214211206202197191
24°F256249242237232228223218211
20°F282271266259254250244239232
16°F305295288282277271264258250

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
5,110
Cooling degree days, base 65°F
1,019
Growing degree days, base 40°F
6,029
Growing degree days, base 45°F
4,745
Growing degree days, base 50°F
3,605
Growing degree days, base 55°F
2,601
Growing degree days, base 60°F
1,737

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,08208
February886010
March703253
April35115185
May12390437
June13220657
July2301764
August5254714
September67116501
October31620214
November632151
December932012

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 1.4 km from Clinton 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 USC00339220 (WFO Wilmington). Public domain.