Crab Orchard climate

Crab Orchard Frost Dates and Growing Season

NOAA 1991-2020 normals for Rockwood 2, 18.6 km from Crab Orchard, elevation 767 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rockwood 2. 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 8 and the first fall freeze around October 31, a growing season of about 203 days.

Median at 36°F
last April 22, first October 22
Median at 32°F
last April 8, first October 31
Median at 28°F
last March 27, first November 9

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

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°F202195190185181176171167160
32°F225218213208203198193187180
28°F253245238232227222218213206
24°F283272266260255250245238230
20°F319306299293286279271264255
16°F350335330323314307300293281

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
96% 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
3,972
Cooling degree days, base 65°F
1,266
Growing degree days, base 40°F
6,827
Growing degree days, base 45°F
5,385
Growing degree days, base 50°F
4,116
Growing degree days, base 55°F
3,009
Growing degree days, base 60°F
2,062

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January86209
February689014
March515187
April25815236
May8194479
June8256699
July0367832
August0332797
September22175603
October22924282
November538164
December772015

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 18.6 km from Crab Orchard. 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 USC00407834 (Rockwood 2). Public domain.