Valley County climate

Valley County Frost Dates and Growing Season

NOAA 1991-2020 normals for Yellowpine, 22.5 km from Valley County, elevation 5050 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Yellowpine. 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 June 12 and the first fall freeze around September 11, a growing season of about 88 days.

Median at 32°F
last June 12, first September 11
Median at 28°F
last May 16, first September 24

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°F–––––––––
32°FJul 5Jun 28Jun 21Jun 16Jun 12Jun 6Jun 2May 28May 21
28°FJun 7May 30May 24May 19May 16May 13May 10May 7May 2
24°FMay 15May 9May 5May 2Apr 30Apr 27Apr 22Apr 17Apr 10
20°FApr 27Apr 19Apr 13Apr 9Apr 5Apr 3Mar 31Mar 25Mar 18
16°FApr 5Apr 1Mar 28Mar 24Mar 19Mar 15Mar 11Mar 7Mar 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°F–––––––––
32°FAug 26Sep 1Sep 5Sep 9Sep 11Sep 14Sep 16Sep 19Sep 23
28°FSep 8Sep 14Sep 18Sep 21Sep 24Sep 26Sep 29Oct 3Oct 10
24°FSep 25Sep 30Oct 4Oct 8Oct 12Oct 17Oct 21Oct 25Nov 1
20°FOct 12Oct 18Oct 23Oct 26Oct 31Nov 3Nov 7Nov 12Nov 18
16°FOct 25Oct 31Nov 5Nov 9Nov 13Nov 16Nov 20Nov 23Nov 27

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°F807165605651463933
32°F114107100948883787062
28°F15014313713212712311711099
24°F192184177172167163157150142
20°F231224217211206201195189180
16°F258250244239234229223216208

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
7,878
Cooling degree days, base 65°F
198
Growing degree days, base 40°F
3,297
Growing degree days, base 45°F
2,365
Growing degree days, base 50°F
1,601
Growing degree days, base 55°F
981
Growing degree days, base 60°F
511

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,26600
February1,02900
March94101
April680016
May476082
June23819252
July6288492
August6178483
September25712234
October629040
November97400
December1,26600

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 22.5 km from Valley 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 USC00109950 (Yellowpine). Public domain.