Powers climate

Powers Frost Dates and Growing Season

NOAA 1991-2020 normals for Powers, 0.7 km from Powers, elevation 230 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Powers. 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 March 21 and the first fall freeze around November 14, a growing season of about 241 days.

Median at 36°F
last April 20, first October 22
Median at 32°F
last March 21, first November 14
Median at 28°F
last February 6, first December 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 9May 4Apr 30Apr 25Apr 20Apr 16Apr 12Apr 8Mar 31
32°FApr 12Apr 5Mar 31Mar 26Mar 21Mar 13Mar 4Feb 26Feb 16
28°FMar 18Mar 1Feb 23Feb 15Feb 6Jan 29Jan 15Dec 31Dec 17
24°FFeb 12Jan 30Jan 15Jan 6Jan 1Dec 28Dec 21Dec 13Dec 2
20°F–––––––––
16°F–––––––––

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 1Oct 9Oct 14Oct 19Oct 22Oct 27Oct 31Nov 5Nov 14
32°FOct 21Oct 28Nov 2Nov 9Nov 14Nov 22Nov 28Dec 3Dec 14
28°FNov 7Nov 17Nov 28Dec 3Dec 9Dec 16Dec 27Jan 6Jan 30
24°FNov 26Dec 4Dec 8Dec 14Dec 20Dec 28Jan 1Jan 11Feb 1
20°F–––––––––
16°F–––––––––

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°F212201194189183176170164155
32°F285271259249241232223213199
28°F359341331322310302291280266
24°F365365365365365357348335319
20°F365365365365365365365365361
16°F365365365365365365365365365

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
92% of years
24°F or colder
46% of years
20°F or colder
9% of years
16°F or colder
1% 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
3,883
Cooling degree days, base 65°F
199
Growing degree days, base 40°F
5,477
Growing degree days, base 45°F
3,835
Growing degree days, base 50°F
2,467
Growing degree days, base 55°F
1,414
Growing degree days, base 60°F
662

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January600021
February501027
March488057
April392197
May2545221
June12716339
July3257490
August2670508
September7545420
October2636216
November476057
December648014

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 0.7 km from Powers. 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 USC00356820 (Powers). Public domain.