Jackson County climate

Jackson County Frost Dates and Growing Season

NOAA 1991-2020 normals for Pt Comfort, 33 km from Jackson County, elevation 20 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pt Comfort. 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 February 1 and the first fall freeze around December 21, a growing season of about 321 days.

Median at 36°F
last February 22, first December 3
Median at 32°F
last February 1, first December 21
Median at 28°F
last January 21, first January 1

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°FMar 18Mar 10Mar 4Feb 27Feb 22Feb 16Feb 8Feb 1Jan 25
32°FMar 4Feb 24Feb 16Feb 6Feb 1Jan 26Jan 19Jan 8Dec 24
28°FFeb 23Feb 9Feb 1Jan 27Jan 21Jan 14Jan 4Dec 28Dec 17
24°FFeb 5Jan 30Jan 26Jan 19Jan 11Jan 5Dec 31Dec 27Dec 19
20°F–––––––––
16°F–––––––––

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°FNov 10Nov 18Nov 24Nov 28Dec 3Dec 7Dec 12Dec 19Dec 28
32°FNov 25Dec 3Dec 9Dec 15Dec 21Dec 26Jan 1Jan 7Jan 18
28°FDec 8Dec 15Dec 22Dec 28Jan 1Jan 6Jan 15Jan 22Feb 6
24°FDec 16Dec 23Dec 28Jan 1Jan 3Jan 8Jan 16Jan 25Feb 1
20°F–––––––––
16°F–––––––––

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°F322308301293285278270263249
32°F361346337330321312304294280
28°F365365365365358349339330313
24°F365365365365365365365365351
20°F365365365365365365365365365
16°F365365365365365365365365365

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
93% of years
28°F or colder
58% of years
24°F or colder
20% of years
20°F or colder
3% of years
16°F or colder
0% 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
1,032
Cooling degree days, base 65°F
3,341
Growing degree days, base 40°F
11,446
Growing degree days, base 45°F
9,650
Growing degree days, base 50°F
7,902
Growing degree days, base 55°F
6,240
Growing degree days, base 60°F
4,711

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January32510201
February20423262
March9278456
April20188618
May1384848
June0537987
July06141,079
August06291,094
September0477927
October16282732
November11191439
December26427260

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 33 km from Jackson 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 USC00417140 (Pt Comfort). Public domain.