Valley County climate

Valley County Frost Dates and Growing Season

NOAA 1991-2020 normals for Ord Evelyn Sharp Fld, 6.8 km from Valley County, elevation 2069 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ord Evelyn Sharp Fld. 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 5 and the first fall freeze around October 3, a growing season of about 150 days.

Median at 36°F
last May 14, first September 26
Median at 32°F
last May 5, first October 3
Median at 28°F
last April 25, first October 12

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 26May 23May 20May 17May 14May 12May 9May 5May 2
32°FMay 19May 14May 10May 8May 5May 3Apr 30Apr 26Apr 22
28°FMay 9May 4May 1Apr 28Apr 25Apr 22Apr 19Apr 14Apr 10
24°FMay 1Apr 25Apr 21Apr 18Apr 14Apr 11Apr 8Apr 4Mar 31
20°FApr 20Apr 15Apr 10Apr 6Apr 4Apr 2Mar 30Mar 25Mar 18
16°FApr 11Apr 5Apr 2Mar 31Mar 27Mar 22Mar 17Mar 13Mar 8

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 13Sep 17Sep 20Sep 23Sep 26Sep 28Oct 1Oct 3Oct 7
32°FSep 20Sep 25Sep 28Sep 30Oct 3Oct 5Oct 8Oct 11Oct 15
28°FSep 28Oct 2Oct 7Oct 10Oct 12Oct 15Oct 17Oct 20Oct 23
24°FOct 7Oct 14Oct 17Oct 20Oct 22Oct 24Oct 26Oct 29Nov 2
20°FOct 18Oct 22Oct 25Oct 28Oct 30Nov 1Nov 4Nov 7Nov 11
16°FOct 25Oct 30Nov 2Nov 4Nov 7Nov 10Nov 13Nov 17Nov 23

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°F150144140136133129126121115
32°F168162158154150146142137131
28°F189182177173170165161156151
24°F208202198193189186181176169
20°F228221215211207204200194188
16°F247241236230226222216211205

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
6,638
Cooling degree days, base 65°F
841
Growing degree days, base 40°F
5,052
Growing degree days, base 45°F
3,944
Growing degree days, base 50°F
2,970
Growing degree days, base 55°F
2,134
Growing degree days, base 60°F
1,424

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,26800
February1,05001
March838121
April515282
May23440294
June35167582
July5302762
August10244699
September12878408
October4856111
November86909
December1,20300

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 6.8 km from Valley County. 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 USW00094958 (Ord Evelyn Sharp Fld). Public domain.