Walhalla climate

Walhalla Frost Dates and Growing Season

NOAA 1991-2020 normals for Walhalla, 1.5 km from Walhalla, elevation 980 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Walhalla. 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 April 11 and the first fall freeze around October 30, a growing season of about 203 days.

Median at 36°F
last April 22, first October 22
Median at 32°F
last April 11, first October 30
Median at 28°F
last March 30, first November 9

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 6May 1Apr 27Apr 24Apr 22Apr 19Apr 16Apr 12Apr 7
32°FApr 25Apr 21Apr 17Apr 14Apr 11Apr 7Apr 4Mar 31Mar 23
28°FApr 16Apr 10Apr 5Apr 2Mar 30Mar 25Mar 21Mar 16Mar 8
24°FApr 2Mar 28Mar 24Mar 19Mar 15Mar 11Mar 5Feb 28Feb 21
20°FMar 21Mar 13Mar 8Mar 2Feb 27Feb 21Feb 15Feb 8Jan 30
16°FMar 7Feb 28Feb 22Feb 15Feb 8Feb 3Jan 29Jan 21Jan 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°FOct 10Oct 14Oct 17Oct 20Oct 22Oct 24Oct 26Oct 29Nov 2
32°FOct 17Oct 22Oct 25Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11
28°FOct 27Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 20Nov 28
24°FNov 5Nov 10Nov 14Nov 17Nov 22Nov 27Dec 1Dec 5Dec 14
20°FNov 17Nov 25Dec 1Dec 3Dec 7Dec 14Dec 22Dec 31Jan 8
16°FDec 1Dec 8Dec 16Dec 24Jan 1Jan 3Jan 9Jan 16Jan 31

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°F201195190186181178175170164
32°F226216211206203199194189181
28°F253244237232227221216210202
24°F286276268261255249243234225
20°F321309301294288282275266255
16°F354340334327318310303295285

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
92% 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
3,483
Cooling degree days, base 65°F
1,396
Growing degree days, base 40°F
7,284
Growing degree days, base 45°F
5,767
Growing degree days, base 50°F
4,422
Growing degree days, base 55°F
3,245
Growing degree days, base 60°F
2,238

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January761021
February608029
March4643112
April21821271
May60113518
June4281727
July0388853
August0361826
September19197628
October19330315
November470290
December687031

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 1.5 km from Walhalla. 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 USC00388887 (Walhalla). Public domain.