Berthold climate

Berthold Frost Dates and Growing Season

NOAA 1991-2020 normals for Foxholm 7 N, 20.3 km from Berthold, elevation 1675 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Foxholm 7 N. 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 September 29, a growing season of about 138 days.

Median at 36°F
last May 20, first September 20
Median at 32°F
last May 11, first September 29
Median at 28°F
last May 2, first October 7

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 12May 31May 27May 23May 20May 17May 14May 10May 6
32°FMay 29May 22May 17May 14May 11May 8May 5May 2Apr 28
28°FMay 20May 13May 8May 5May 2Apr 30Apr 27Apr 23Apr 17
24°FMay 8May 2Apr 29Apr 26Apr 22Apr 19Apr 16Apr 13Apr 9
20°FApr 29Apr 24Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Apr 1
16°FApr 20Apr 14Apr 11Apr 7Apr 5Apr 3Apr 1Mar 29Mar 21

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

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°F14113413012612211711210594
32°F158152147143138134130124115
28°F178171166162157153149143134
24°F198191186181177173168162153
20°F216209204200196192188182172
16°F232225220216212208204199191

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
8,782
Cooling degree days, base 65°F
514
Growing degree days, base 40°F
4,129
Growing degree days, base 45°F
3,171
Growing degree days, base 50°F
2,327
Growing degree days, base 55°F
1,600
Growing degree days, base 60°F
990

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65700
February1,39300
March1,15504
April688035
May32218213
June7781457
July19189635
August28181618
September21343303
October640257
November1,08304
December1,51000

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 20.3 km from Berthold. 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 USC00323217 (Foxholm 7 N). Public domain.