Johnsonville climate

Johnsonville Frost Dates and Growing Season

NOAA 1991-2020 normals for Hemingway 8 Ese, 16.7 km from Johnsonville, elevation 40 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hemingway 8 Ese. 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 23 and the first fall freeze around November 15, a growing season of about 240 days.

Median at 36°F
last April 2, first November 4
Median at 32°F
last March 23, first November 15
Median at 28°F
last March 4, first December 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°FApr 18Apr 13Apr 8Apr 5Apr 2Mar 31Mar 27Mar 23Mar 18
32°FApr 7Apr 2Mar 29Mar 26Mar 23Mar 19Mar 15Mar 9Mar 2
28°FMar 27Mar 20Mar 15Mar 9Mar 4Mar 1Feb 24Feb 15Feb 5
24°FMar 14Mar 5Feb 28Feb 21Feb 12Feb 5Jan 31Jan 24Jan 11
20°FFeb 28Feb 15Feb 5Jan 31Jan 26Jan 21Jan 16Jan 8Dec 31
16°FFeb 8Feb 1Jan 26Jan 22Jan 18Jan 13Jan 8Jan 2Dec 27

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 30Nov 1Nov 4Nov 6Nov 10Nov 14Nov 20
32°FNov 1Nov 4Nov 8Nov 12Nov 15Nov 19Nov 23Dec 1Dec 5
28°FNov 11Nov 16Nov 21Nov 26Dec 1Dec 4Dec 10Dec 19Jan 1
24°FNov 24Dec 1Dec 7Dec 12Dec 20Dec 28Jan 1Jan 9Jan 21
20°FDec 9Dec 17Dec 26Jan 1Jan 6Jan 11Jan 16Jan 22Feb 3
16°FDec 18Dec 30Jan 4Jan 8Jan 13Jan 17Jan 22Jan 28Feb 5

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°F239229224220216211207202196
32°F269259251246240236230224216
28°F303292285277271265259251240
24°F344333323314307301294284271
20°F365365360351342335327315303
16°F365365365365365365362349334

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
96% 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
2,453
Cooling degree days, base 65°F
1,933
Growing degree days, base 40°F
8,703
Growing degree days, base 45°F
7,040
Growing degree days, base 50°F
5,520
Growing degree days, base 55°F
4,155
Growing degree days, base 60°F
2,952

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January578280
February452487
March34212193
April12961389
May24176617
June0365814
July0480945
August0448913
September3285732
October10182451
November32313186
December5015113

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 16.7 km from Johnsonville. 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 USC00384111 (Hemingway 8 Ese). Public domain.