Wanblee climate

Wanblee Frost Dates and Growing Season

NOAA 1991-2020 normals for Longvalley, 18 km from Wanblee, elevation 2470 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Longvalley. 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 9 and the first fall freeze around October 1, a growing season of about 143 days.

Median at 36°F
last May 20, first September 24
Median at 32°F
last May 9, first October 1
Median at 28°F
last May 1, first October 11

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 2May 29May 26May 23May 20May 17May 14May 11May 7
32°FMay 24May 19May 15May 12May 9May 7May 4May 1Apr 26
28°FMay 14May 9May 6May 3May 1Apr 28Apr 24Apr 20Apr 15
24°FMay 3Apr 29Apr 25Apr 22Apr 19Apr 16Apr 12Apr 8Apr 3
20°FApr 24Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 29Mar 21
16°FApr 16Apr 11Apr 7Apr 3Apr 1Mar 29Mar 24Mar 16Mar 9

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 10Sep 15Sep 19Sep 21Sep 24Sep 26Sep 28Oct 1Oct 4
32°FSep 17Sep 23Sep 27Sep 29Oct 1Oct 4Oct 6Oct 11Oct 15
28°FSep 25Oct 1Oct 4Oct 8Oct 11Oct 14Oct 17Oct 20Oct 24
24°FOct 4Oct 9Oct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 3
20°FOct 11Oct 17Oct 22Oct 25Oct 28Nov 1Nov 4Nov 7Nov 14
16°FOct 19Oct 26Oct 30Nov 2Nov 5Nov 8Nov 12Nov 16Nov 21

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°F143137133129125122117114107
32°F162155151147143139135130123
28°F183177171166162157153148141
24°F203195189185180176172166160
20°F224216211206201196191185178
16°F246237231225220215209203193

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
6,622
Cooling degree days, base 65°F
841
Growing degree days, base 40°F
5,049
Growing degree days, base 45°F
3,922
Growing degree days, base 50°F
2,951
Growing degree days, base 55°F
2,113
Growing degree days, base 60°F
1,408

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22002
February1,04003
March850026
April552377
May27226252
June56133528
July8302759
August14270721
September121100438
October4868126
November854018
December1,15001

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 18 km from Wanblee. 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 USC00394983 (Longvalley). Public domain.