Ottawa County climate

Ottawa County Frost Dates and Growing Season

NOAA 1991-2020 normals for Sandusky, 19.4 km from Ottawa County, elevation 584 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sandusky. 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 10 and the first fall freeze around November 5, a growing season of about 209 days.

Median at 36°F
last April 21, first October 26
Median at 32°F
last April 10, first November 5
Median at 28°F
last April 1, first November 16

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 5May 1Apr 28Apr 24Apr 21Apr 19Apr 16Apr 13Apr 8
32°FApr 23Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Apr 2Mar 31
28°FApr 14Apr 9Apr 5Apr 3Apr 1Mar 30Mar 27Mar 22Mar 16
24°FApr 3Mar 31Mar 27Mar 23Mar 20Mar 17Mar 14Mar 10Mar 5
20°FMar 26Mar 20Mar 16Mar 14Mar 11Mar 8Mar 5Mar 2Feb 24
16°FMar 17Mar 12Mar 8Mar 5Mar 2Feb 28Feb 24Feb 17Feb 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°FOct 12Oct 17Oct 21Oct 23Oct 26Oct 29Nov 1Nov 4Nov 9
32°FOct 23Oct 29Nov 1Nov 3Nov 5Nov 8Nov 11Nov 15Nov 20
28°FNov 3Nov 7Nov 10Nov 13Nov 16Nov 20Nov 24Nov 28Dec 2
24°FNov 11Nov 15Nov 20Nov 24Nov 27Dec 1Dec 3Dec 8Dec 14
20°FNov 19Nov 26Dec 1Dec 4Dec 7Dec 11Dec 16Dec 20Dec 25
16°FNov 28Dec 4Dec 9Dec 14Dec 18Dec 22Dec 25Dec 31Jan 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°F206199194190186182177173167
32°F227221216213209205201196190
28°F253244239234230226222217211
24°F274266261257252248242237229
20°F297289282277273267262256248
16°F316307302296292287282277267

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
5,653
Cooling degree days, base 65°F
953
Growing degree days, base 40°F
5,609
Growing degree days, base 45°F
4,404
Growing degree days, base 50°F
3,338
Growing degree days, base 55°F
2,411
Growing degree days, base 60°F
1,615

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,14403
February97403
March839123
April4798103
May18758343
June23196622
July1303767
August3256718
September62113502
October31918203
November647143
December97507

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 19.4 km from Ottawa County. 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 USW00014846 (Sandusky). Public domain.