Huron County climate

Huron County Frost Dates and Growing Season

NOAA 1991-2020 normals for Norwalk Wwtp, 13.5 km from Huron County, elevation 670 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Norwalk Wwtp. 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 25 and the first fall freeze around October 25, a growing season of about 183 days.

Median at 36°F
last May 4, first October 13
Median at 32°F
last April 25, first October 25
Median at 28°F
last April 12, first November 5

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 20May 15May 10May 7May 4May 2Apr 29Apr 26Apr 21
32°FMay 9May 4May 1Apr 28Apr 25Apr 22Apr 19Apr 16Apr 11
28°FApr 28Apr 22Apr 19Apr 16Apr 12Apr 8Apr 6Apr 3Mar 31
24°FApr 16Apr 10Apr 6Apr 3Apr 1Mar 30Mar 27Mar 23Mar 18
20°FApr 5Apr 1Mar 29Mar 26Mar 22Mar 19Mar 16Mar 12Mar 6
16°FMar 29Mar 23Mar 19Mar 16Mar 13Mar 10Mar 7Mar 2Feb 25

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 30Oct 3Oct 7Oct 10Oct 13Oct 15Oct 19Oct 23Oct 27
32°FOct 11Oct 15Oct 20Oct 22Oct 25Oct 28Oct 31Nov 3Nov 7
28°FOct 22Oct 27Oct 31Nov 2Nov 5Nov 7Nov 11Nov 15Nov 20
24°FNov 1Nov 6Nov 9Nov 12Nov 16Nov 20Nov 25Nov 30Dec 4
20°FNov 10Nov 16Nov 20Nov 25Nov 29Dec 2Dec 6Dec 10Dec 18
16°FNov 20Nov 28Dec 1Dec 5Dec 9Dec 13Dec 18Dec 22Dec 27

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°F178172168164160157152148141
32°F202195191187183179174170163
28°F228220215210206201196191186
24°F251243237232228224219214208
20°F273266260255250245241235228
16°F295287280275271266261254246

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
6,083
Cooling degree days, base 65°F
827
Growing degree days, base 40°F
5,282
Growing degree days, base 45°F
4,120
Growing degree days, base 50°F
3,097
Growing degree days, base 55°F
2,207
Growing degree days, base 60°F
1,446

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20302
February1,02803
March878123
April5068102
May21258329
June40176587
July6263722
August11211665
September9595452
October37815170
November699036
December1,02905

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 13.5 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 USC00336118 (Norwalk Wwtp). Public domain.