Jackson climate

Jackson Frost Dates and Growing Season

NOAA 1991-2020 normals for N Conway, 10.6 km from Jackson, elevation 522 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for N Conway. 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 May 7 and the first fall freeze around October 5, a growing season of about 150 days.

Median at 36°F
last May 18, first September 26
Median at 32°F
last May 7, first October 5
Median at 28°F
last April 26, first October 17

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 31May 27May 23May 20May 18May 16May 13May 10May 6
32°FMay 19May 16May 13May 10May 7May 5May 2Apr 30Apr 27
28°FMay 9May 5May 1Apr 29Apr 26Apr 24Apr 21Apr 18Apr 13
24°FApr 26Apr 20Apr 17Apr 14Apr 11Apr 9Apr 7Apr 4Apr 2
20°FApr 13Apr 9Apr 6Apr 4Apr 2Apr 1Mar 30Mar 26Mar 20
16°FApr 5Apr 2Mar 31Mar 28Mar 25Mar 22Mar 19Mar 16Mar 12

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 13Sep 18Sep 21Sep 24Sep 26Sep 28Oct 1Oct 3Oct 7
32°FSep 23Sep 28Oct 1Oct 2Oct 5Oct 7Oct 10Oct 15Oct 20
28°FOct 1Oct 5Oct 9Oct 13Oct 17Oct 20Oct 24Oct 29Nov 4
24°FOct 13Oct 19Oct 24Oct 28Nov 1Nov 3Nov 6Nov 11Nov 15
20°FOct 30Nov 2Nov 7Nov 11Nov 14Nov 17Nov 20Nov 23Nov 29
16°FNov 12Nov 17Nov 20Nov 23Nov 26Nov 29Dec 1Dec 4Dec 9

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°F146141137133130127123119113
32°F168161156153150146143138132
28°F195187183178174168164160154
24°F219213208204200196192186179
20°F244238233229225222217212205
16°F265258253250246242238233227

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
7,507
Cooling degree days, base 65°F
411
Growing degree days, base 40°F
4,095
Growing degree days, base 45°F
3,091
Growing degree days, base 50°F
2,221
Growing degree days, base 55°F
1,476
Growing degree days, base 60°F
866

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,39700
February1,19700
March1,05303
April655133
May31215201
June9079441
July16162611
August28118555
September18434309
October539163
November84807
December1,18900

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 10.6 km from Jackson. 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 USC00275995 (N Conway). Public domain.