Acme climate

Acme Frost Dates and Growing Season

NOAA 1991-2020 normals for Donegal 2 Nw, 2 km from Acme, elevation 1800 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Donegal 2 Nw. 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 30 and the first fall freeze around October 17, a growing season of about 170 days.

Median at 36°F
last May 11, first October 6
Median at 32°F
last April 30, first October 17
Median at 28°F
last April 17, first October 30

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 29May 24May 20May 16May 11May 8May 4Apr 30Apr 25
32°FMay 18May 11May 7May 2Apr 30Apr 26Apr 23Apr 19Apr 15
28°FMay 8Apr 30Apr 25Apr 20Apr 17Apr 14Apr 11Apr 6Apr 3
24°FApr 20Apr 15Apr 11Apr 7Apr 5Apr 2Mar 31Mar 27Mar 22
20°FApr 9Apr 4Apr 1Mar 30Mar 26Mar 23Mar 20Mar 16Mar 11
16°FApr 1Mar 28Mar 23Mar 20Mar 17Mar 14Mar 11Mar 7Mar 1

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 23Sep 27Oct 1Oct 3Oct 6Oct 8Oct 11Oct 14Oct 19
32°FOct 3Oct 7Oct 11Oct 14Oct 17Oct 20Oct 23Oct 26Oct 31
28°FOct 13Oct 20Oct 24Oct 27Oct 30Nov 1Nov 4Nov 8Nov 13
24°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 17Nov 23Nov 29
20°FNov 6Nov 10Nov 14Nov 18Nov 23Nov 26Nov 30Dec 4Dec 10
16°FNov 14Nov 21Nov 26Nov 30Dec 4Dec 7Dec 12Dec 19Dec 26

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°F168162156152147143137132125
32°F191184179175170166160154146
28°F217210205200195191185180171
24°F242235229225220216212207199
20°F265256250246241236232226219
16°F287279273266261256250244236

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
6,105
Cooling degree days, base 65°F
526
Growing degree days, base 40°F
4,897
Growing degree days, base 45°F
3,717
Growing degree days, base 50°F
2,688
Growing degree days, base 55°F
1,813
Growing degree days, base 60°F
1,089

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,17203
February98705
March874020
April4956103
May23333289
June53103500
July16175625
August22149592
September12253385
October4177134
November713026
December1,00306

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 2 km from Acme. 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 USC00362183 (Donegal 2 Nw). Public domain.