Perry climate

Perry Frost Dates and Growing Season

NOAA 1991-2020 normals for Perry, 0.3 km from Perry, elevation 950 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Perry. 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 25 and the first fall freeze around October 10, a growing season of about 166 days.

Median at 36°F
last May 5, first September 30
Median at 32°F
last April 25, first October 10
Median at 28°F
last April 16, first October 22

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 17May 13May 9May 7May 5May 3Apr 30Apr 26Apr 22
32°FMay 8May 5May 2Apr 28Apr 25Apr 22Apr 19Apr 16Apr 12
28°FApr 30Apr 25Apr 22Apr 18Apr 16Apr 13Apr 10Apr 6Apr 2
24°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 3Apr 1Mar 28Mar 21
20°FApr 12Apr 5Apr 2Mar 31Mar 27Mar 23Mar 20Mar 15Mar 10
16°FApr 2Mar 28Mar 23Mar 19Mar 16Mar 13Mar 10Mar 6Mar 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 17Sep 21Sep 25Sep 27Sep 30Oct 2Oct 5Oct 9Oct 13
32°FSep 25Sep 30Oct 3Oct 7Oct 10Oct 13Oct 16Oct 19Oct 24
28°FOct 5Oct 12Oct 15Oct 19Oct 22Oct 24Oct 27Oct 30Nov 3
24°FOct 19Oct 24Oct 27Oct 29Nov 1Nov 2Nov 5Nov 8Nov 13
20°FOct 28Nov 1Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 25
16°FNov 2Nov 7Nov 10Nov 14Nov 17Nov 20Nov 25Nov 30Dec 3

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°F164158154150146143140135128
32°F185179175169166162158153146
28°F207200196191187184179174167
24°F227221216211208203199195188
20°F249241236231227222217212204
16°F270261256251246240236230221

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
6,740
Cooling degree days, base 65°F
895
Growing degree days, base 40°F
5,243
Growing degree days, base 45°F
4,131
Growing degree days, base 50°F
3,139
Growing degree days, base 55°F
2,266
Growing degree days, base 60°F
1,518

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40000
February1,14701
March880121
April4877106
May19655338
June24200626
July4297758
August10229683
September11695435
October43013151
November831020
December1,21701

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 0.3 km from Perry. 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 USC00136566 (Perry). Public domain.