Defiance County climate

Defiance County Frost Dates and Growing Season

NOAA 1991-2020 normals for Defiance Mem AP, 5.3 km from Defiance County, elevation 708 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Defiance Mem AP. 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 October 17, a growing season of about 170 days.

Median at 36°F
last May 8, first October 5
Median at 32°F
last April 28, first October 17
Median at 28°F
last April 15, first October 30

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 23May 17May 14May 11May 8May 5May 1Apr 29Apr 22
32°FMay 14May 8May 4May 1Apr 28Apr 24Apr 21Apr 17Apr 13
28°FMay 3Apr 28Apr 22Apr 19Apr 15Apr 12Apr 9Apr 6Apr 1
24°FApr 19Apr 14Apr 9Apr 6Apr 3Mar 31Mar 28Mar 24Mar 19
20°FApr 6Apr 1Mar 30Mar 26Mar 24Mar 20Mar 17Mar 13Mar 6
16°FMar 30Mar 25Mar 21Mar 17Mar 14Mar 10Mar 6Mar 3Feb 26

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 21Sep 26Sep 29Oct 2Oct 5Oct 7Oct 10Oct 13Oct 18
32°FOct 1Oct 6Oct 11Oct 14Oct 17Oct 20Oct 23Oct 27Nov 1
28°FOct 15Oct 20Oct 23Oct 26Oct 30Nov 1Nov 3Nov 7Nov 12
24°FOct 26Nov 1Nov 3Nov 6Nov 9Nov 13Nov 16Nov 20Nov 26
20°FNov 7Nov 11Nov 15Nov 19Nov 22Nov 26Nov 29Dec 3Dec 11
16°FNov 14Nov 21Nov 25Nov 29Dec 2Dec 5Dec 10Dec 16Dec 22

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°F168162157154150147142137130
32°F192184178175170166161156150
28°F216208203198195191186180172
24°F242234229224220215211206199
20°F268260253249244239234228221
16°F289280275270265260255248240

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
6,179
Cooling degree days, base 65°F
747
Growing degree days, base 40°F
5,164
Growing degree days, base 45°F
4,012
Growing degree days, base 50°F
2,994
Growing degree days, base 55°F
2,109
Growing degree days, base 60°F
1,358

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23401
February1,04202
March855125
April4795101
May20247323
June32166584
July4250711
August11192646
September10875420
October40411150
November732027
December1,07604

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 5.3 km from Defiance 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 USW00004851 (Defiance Mem AP). Public domain.