Huron County climate

Huron County Frost Dates and Growing Season

NOAA 1991-2020 normals for Port Hope, 13.4 km from Huron County, elevation 590 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Port Hope. 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 28 and the first fall freeze around November 3, a growing season of about 187 days.

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

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

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°F183175171166162158154149143
32°F207200196191187183178173166
28°F234226221217213209204199192
24°F260252246241237232227222215
20°F281274268263259254249244237
16°F299292288283279274269264257

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
6,942
Cooling degree days, base 65°F
446
Growing degree days, base 40°F
4,288
Growing degree days, base 45°F
3,236
Growing degree days, base 50°F
2,331
Growing degree days, base 55°F
1,558
Growing degree days, base 60°F
919

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25700
February1,12100
March1,01207
April669135
May37615162
June12075407
July21156600
August17137584
September12355385
October4168131
November741019
December1,07001

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 13.4 km from Huron 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 USW00094898 (Port Hope). Public domain.