Washington County climate

Washington County Frost Dates and Growing Season

NOAA 1991-2020 normals for Akron 4 E, 21.1 km from Washington County, elevation 4542 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Akron 4 E. 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 6, a growing season of about 149 days.

Median at 36°F
last May 19, first September 27
Median at 32°F
last May 8, first October 6
Median at 28°F
last April 30, 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°FMay 31May 27May 24May 21May 19May 16May 14May 11May 7
32°FMay 22May 16May 14May 11May 8May 6May 3May 1Apr 27
28°FMay 11May 7May 4May 1Apr 30Apr 27Apr 23Apr 19Apr 14
24°FMay 3Apr 29Apr 25Apr 21Apr 18Apr 15Apr 11Apr 7Mar 31
20°FApr 22Apr 17Apr 13Apr 8Apr 5Apr 1Mar 28Mar 23Mar 16
16°FApr 12Apr 6Apr 1Mar 28Mar 24Mar 20Mar 14Mar 9Mar 4

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 15Sep 20Sep 23Sep 25Sep 27Sep 30Oct 2Oct 4Oct 8
32°FSep 25Sep 29Oct 1Oct 4Oct 6Oct 8Oct 11Oct 13Oct 17
28°FOct 3Oct 6Oct 10Oct 13Oct 15Oct 17Oct 19Oct 22Oct 26
24°FOct 10Oct 14Oct 18Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
20°FOct 17Oct 22Oct 25Oct 29Nov 1Nov 3Nov 6Nov 10Nov 16
16°FOct 25Oct 31Nov 3Nov 6Nov 9Nov 13Nov 16Nov 20Nov 24

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°F146142138135131128123119114
32°F166161156153149146142138132
28°F186179174170168164161157151
24°F206199194190186182178173166
20°F231223218212207203198192185
16°F254247240234228223218211200

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
6,216
Cooling degree days, base 65°F
815
Growing degree days, base 40°F
5,118
Growing degree days, base 45°F
3,960
Growing degree days, base 50°F
2,959
Growing degree days, base 55°F
2,107
Growing degree days, base 60°F
1,395

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12701
February95202
March769025
April534278
May27525256
June51149549
July6301759
August12243696
September12091433
October4585138
November800021
December1,11301

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 21.1 km from Washington County. 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 USC00050109 (Akron 4 E). Public domain.