Black Forest climate

Black Forest Frost Dates and Growing Season

NOAA 1991-2020 normals for Black Forest 6WNW, 8.9 km from Black Forest, elevation 6957 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Black Forest 6WNW. 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 11 and the first fall freeze around October 6, a growing season of about 147 days.

Median at 36°F
last May 23, first September 29
Median at 32°F
last May 11, first October 6
Median at 28°F
last May 2, first October 16

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 5May 31May 28May 25May 23May 20May 17May 14May 10
32°FMay 25May 20May 16May 13May 11May 8May 5May 3Apr 30
28°FMay 16May 11May 7May 5May 2Apr 30Apr 28Apr 24Apr 19
24°FMay 8May 2Apr 29Apr 26Apr 22Apr 19Apr 16Apr 12Apr 6
20°FApr 27Apr 21Apr 18Apr 13Apr 9Apr 5Apr 2Mar 29Mar 21
16°FApr 18Apr 9Apr 4Mar 31Mar 26Mar 21Mar 16Mar 12Mar 6

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 17Sep 21Sep 25Sep 27Sep 29Oct 1Oct 4Oct 6Oct 10
32°FSep 25Sep 30Oct 2Oct 5Oct 6Oct 9Oct 12Oct 15Oct 19
28°FOct 3Oct 6Oct 9Oct 13Oct 16Oct 18Oct 21Oct 24Oct 29
24°FOct 11Oct 15Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2Nov 7
20°FOct 18Oct 22Oct 27Oct 31Nov 2Nov 5Nov 8Nov 12Nov 17
16°FOct 23Nov 1Nov 4Nov 6Nov 10Nov 14Nov 18Nov 21Nov 26

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°F147140136132129125121116110
32°F164159155151147144139134128
28°F181176172168164160156152145
24°F204197191188183179175171165
20°F229222215210206201196190182
16°F254244237231227221215209201

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
6,183
Cooling degree days, base 65°F
440
Growing degree days, base 40°F
4,569
Growing degree days, base 45°F
3,406
Growing degree days, base 50°F
2,427
Growing degree days, base 55°F
1,606
Growing degree days, base 60°F
942

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,02301
February91406
March785123
April593151
May34412200
June8077448
July11172626
August29125561
September14847359
October4735128
November765023
December1,01803

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 8.9 km from Black Forest. 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 USC00050756 (Black Forest 6WNW). Public domain.