Allenton climate

Allenton Frost Dates and Growing Season

NOAA 1991-2020 normals for Hartford Wwtp, 11.5 km from Allenton, elevation 961 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hartford Wwtp. 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 8 and the first fall freeze around October 3, a growing season of about 148 days.

Median at 36°F
last May 20, first September 25
Median at 32°F
last May 8, first October 3
Median at 28°F
last April 27, first October 15

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 2May 31May 27May 23May 20May 17May 13May 9May 5
32°FMay 24May 18May 14May 11May 8May 5May 1Apr 29Apr 24
28°FMay 12May 6May 2Apr 29Apr 27Apr 23Apr 20Apr 16Apr 11
24°FApr 29Apr 24Apr 20Apr 17Apr 13Apr 10Apr 7Apr 3Mar 31
20°FApr 18Apr 11Apr 8Apr 5Apr 3Apr 1Mar 30Mar 24Mar 18
16°FApr 7Apr 2Mar 31Mar 27Mar 23Mar 21Mar 18Mar 15Mar 10

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 12Sep 16Sep 19Sep 22Sep 25Sep 28Sep 30Oct 3Oct 6
32°FSep 20Sep 25Sep 29Oct 1Oct 3Oct 5Oct 8Oct 12Oct 16
28°FSep 30Oct 5Oct 9Oct 12Oct 15Oct 18Oct 21Oct 25Oct 30
24°FOct 12Oct 17Oct 21Oct 25Oct 27Oct 30Nov 1Nov 5Nov 10
20°FOct 26Oct 31Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 22
16°FNov 3Nov 7Nov 11Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1

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°F147140135132128124120116109
32°F168161156152148144141135127
28°F191184179175171167162157150
24°F216209204199195190186181173
20°F240232228223219214210205199
16°F260252247242238235231226218

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
7,781
Cooling degree days, base 65°F
434
Growing degree days, base 40°F
4,171
Growing degree days, base 45°F
3,164
Growing degree days, base 50°F
2,284
Growing degree days, base 55°F
1,528
Growing degree days, base 60°F
900

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48200
February1,24200
March1,039010
April639247
May31823214
June8095466
July26156595
August41115539
September18740316
October534487
November90509
December1,29100

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 11.5 km from Allenton. 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 USC00473453 (Hartford Wwtp). Public domain.