Jack climate

Jack Frost Dates and Growing Season

NOAA 1991-2020 normals for Troy 2 W, 24 km from Jack, elevation 472 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Troy 2 W. 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 March 17 and the first fall freeze around November 16, a growing season of about 242 days.

Median at 36°F
last April 1, first November 4
Median at 32°F
last March 17, first November 16
Median at 28°F
last March 5, first November 29

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°FApr 18Apr 12Apr 7Apr 4Apr 1Mar 29Mar 25Mar 20Mar 13
32°FApr 3Mar 29Mar 25Mar 21Mar 17Mar 13Mar 9Mar 3Feb 25
28°FMar 24Mar 18Mar 14Mar 9Mar 5Feb 28Feb 23Feb 15Feb 2
24°FMar 14Mar 6Feb 28Feb 22Feb 16Feb 8Feb 1Jan 25Jan 10
20°FMar 4Feb 22Feb 11Feb 3Jan 30Jan 23Jan 15Jan 4Dec 26
16°FFeb 17Feb 4Jan 31Jan 27Jan 21Jan 14Jan 9Jan 3Dec 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°FOct 22Oct 27Oct 31Nov 2Nov 4Nov 7Nov 10Nov 15Nov 20
32°FNov 1Nov 5Nov 9Nov 12Nov 16Nov 19Nov 22Nov 27Dec 4
28°FNov 10Nov 16Nov 20Nov 25Nov 29Dec 2Dec 7Dec 18Jan 1
24°FNov 21Nov 30Dec 4Dec 9Dec 18Dec 28Jan 1Jan 9Jan 23
20°FDec 4Dec 13Dec 23Dec 30Jan 3Jan 9Jan 17Jan 26Feb 5
16°FDec 20Dec 31Jan 3Jan 8Jan 12Jan 19Jan 26Feb 1Feb 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°F244234228223219214209203196
32°F270261253248242236232226218
28°F306294285279272266260252245
24°F343332322314306300291283270
20°F365365357346337330323313302
16°F365365365365365365354339327

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
97% of years
20°F or colder
74% of years
16°F or colder
36% 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
2,163
Cooling degree days, base 65°F
1,990
Growing degree days, base 40°F
9,032
Growing degree days, base 45°F
7,342
Growing degree days, base 50°F
5,771
Growing degree days, base 55°F
4,336
Growing degree days, base 60°F
3,067

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January5383103
February3886130
March26021260
April9565422
May19206653
June0369819
July0448913
August0440905
September4309756
October86102483
November29717206
December4774122

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 24 km from Jack. 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 USW00023801 (Troy 2 W). Public domain.