Jay County climate

Jay County Frost Dates and Growing Season

NOAA 1991-2020 normals for Portland 1 Sw, 2.5 km from Jay County, elevation 910 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Portland 1 Sw. 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 15, a growing season of about 171 days.

Median at 36°F
last May 7, first October 5
Median at 32°F
last April 28, first October 15
Median at 28°F
last April 15, first October 28

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 21May 16May 13May 10May 7May 4May 2Apr 29Apr 24
32°FMay 14May 8May 4May 1Apr 28Apr 24Apr 21Apr 18Apr 13
28°FMay 2Apr 27Apr 22Apr 19Apr 15Apr 12Apr 9Apr 5Apr 1
24°FApr 18Apr 13Apr 8Apr 5Apr 3Mar 31Mar 28Mar 24Mar 18
20°FApr 7Apr 2Mar 31Mar 28Mar 24Mar 20Mar 17Mar 13Mar 6
16°FMar 30Mar 25Mar 20Mar 17Mar 14Mar 10Mar 6Mar 1Feb 23

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 23Sep 28Oct 1Oct 3Oct 5Oct 8Oct 10Oct 13Oct 18
32°FOct 1Oct 6Oct 10Oct 12Oct 15Oct 18Oct 21Oct 25Oct 30
28°FOct 11Oct 17Oct 21Oct 24Oct 28Oct 30Nov 1Nov 4Nov 10
24°FOct 22Oct 28Nov 1Nov 3Nov 5Nov 9Nov 13Nov 18Nov 24
20°FNov 1Nov 6Nov 11Nov 14Nov 18Nov 23Nov 27Dec 1Dec 7
16°FNov 11Nov 18Nov 24Nov 28Dec 1Dec 6Dec 11Dec 15Dec 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°F170163158154151147144139132
32°F192184179174171166162157150
28°F215207202198194190184179171
24°F239231226221217213208203195
20°F265256248243239234229223215
16°F288279272266261256251245235

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
6,090
Cooling degree days, base 65°F
771
Growing degree days, base 40°F
5,257
Growing degree days, base 45°F
4,094
Growing degree days, base 50°F
3,064
Growing degree days, base 55°F
2,163
Growing degree days, base 60°F
1,397

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22702
February1,02803
March839129
April4667115
May19453339
June34170587
July5247707
August12191643
September10587436
October39615167
November727133
December1,05704

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 2.5 km from Jay 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 USC00127069 (Portland 1 Sw). Public domain.