Pomeroy climate

Pomeroy Frost Dates and Growing Season

NOAA 1991-2020 normals for Pomeroy, 1.4 km from Pomeroy, elevation 1934 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pomeroy. 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 2 and the first fall freeze around October 4, a growing season of about 155 days.

Median at 36°F
last May 19, first September 19
Median at 32°F
last May 2, first October 4
Median at 28°F
last April 11, first October 19

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 8Jun 1May 28May 23May 19May 16May 12May 8May 3
32°FMay 19May 14May 9May 6May 2Apr 30Apr 26Apr 22Apr 15
28°FMay 4Apr 29Apr 23Apr 16Apr 11Apr 7Apr 2Mar 29Mar 21
24°FApr 11Apr 1Mar 26Mar 21Mar 17Mar 13Mar 9Mar 4Feb 27
20°FMar 20Mar 13Mar 8Mar 4Feb 28Feb 25Feb 19Feb 14Feb 3
16°FMar 7Mar 1Feb 25Feb 20Feb 15Feb 8Jan 31Jan 20Jan 3

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°FAug 31Sep 6Sep 10Sep 15Sep 19Sep 23Sep 26Sep 30Oct 5
32°FSep 17Sep 24Sep 28Oct 1Oct 4Oct 8Oct 12Oct 17Oct 24
28°FOct 2Oct 7Oct 12Oct 16Oct 19Oct 22Oct 27Nov 1Nov 7
24°FOct 13Oct 19Oct 23Oct 28Nov 1Nov 5Nov 10Nov 17Nov 25
20°FOct 21Oct 29Nov 3Nov 9Nov 16Nov 21Nov 27Dec 1Dec 9
16°FOct 31Nov 11Nov 20Nov 26Dec 1Dec 6Dec 12Dec 18Dec 30

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°F14713913312712211711210596
32°F182172165161155151146140131
28°F220209203196189184178170161
24°F258248240234227221214206195
20°F298285277269261254245236224
16°F336322310301294285277268255

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
99% 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
5,928
Cooling degree days, base 65°F
396
Growing degree days, base 40°F
4,393
Growing degree days, base 45°F
3,180
Growing degree days, base 50°F
2,195
Growing degree days, base 55°F
1,415
Growing degree days, base 60°F
815

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January96902
February80102
March704011
April512053
May30312202
June14337345
July31155589
August35157587
September17534318
October499175
November762011
December99502

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 1.4 km from Pomeroy. 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 USC00456610 (Pomeroy). Public domain.