Limestone climate

Limestone Frost Dates and Growing Season

NOAA 1991-2020 normals for Limestone 4 Nnw, 7.1 km from Limestone, elevation 737 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Limestone 4 Nnw. 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 16 and the first fall freeze around September 24, a growing season of about 129 days.

Median at 36°F
last May 31, first September 14
Median at 32°F
last May 16, first September 24
Median at 28°F
last May 2, first October 4

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°FJun 13Jun 8Jun 5Jun 2May 31May 29May 26May 22May 16
32°FJun 1May 26May 23May 19May 16May 13May 9May 5May 1
28°FMay 16May 10May 7May 5May 2May 1Apr 29Apr 26Apr 22
24°FMay 3Apr 30Apr 28Apr 26Apr 24Apr 21Apr 19Apr 16Apr 11
20°FApr 26Apr 22Apr 19Apr 17Apr 14Apr 12Apr 9Apr 6Apr 3
16°FApr 20Apr 16Apr 12Apr 8Apr 6Apr 5Apr 3Apr 1Mar 29

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 1Sep 6Sep 9Sep 12Sep 14Sep 16Sep 19Sep 22Sep 27
32°FSep 12Sep 16Sep 20Sep 22Sep 24Sep 27Sep 30Oct 2Oct 5
28°FSep 23Sep 27Sep 30Oct 2Oct 4Oct 7Oct 10Oct 14Oct 19
24°FOct 3Oct 7Oct 12Oct 15Oct 18Oct 22Oct 26Oct 30Nov 4
20°FOct 17Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 15
16°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 13Nov 17Nov 21Nov 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°F124117112108104100979386
32°F148141136133129125121116109
28°F171165161157153150146142136
24°F197190185181178174169164158
20°F218212208204199196193188182
16°F235228224220217213210205199

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
9,724
Cooling degree days, base 65°F
131
Growing degree days, base 40°F
3,020
Growing degree days, base 45°F
2,162
Growing degree days, base 50°F
1,435
Growing degree days, base 55°F
836
Growing degree days, base 60°F
391

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,72300
February1,49000
March1,30401
April85706
May467595
June19622281
July7654443
August10441402
September31910181
October702025
November1,02902
December1,45900

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 7.1 km from Limestone. 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 USW00094645 (Limestone 4 Nnw). Public domain.