Mohall climate

Mohall Frost Dates and Growing Season

NOAA 1991-2020 normals for Mohall, 0.4 km from Mohall, elevation 1641 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mohall. 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 17 and the first fall freeze around September 23, a growing season of about 127 days.

Median at 36°F
last May 26, first September 15
Median at 32°F
last May 17, first September 23
Median at 28°F
last May 9, first October 1

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 7Jun 3May 31May 29May 26May 24May 21May 19May 15
32°FMay 30May 25May 22May 20May 17May 15May 12May 10May 6
28°FMay 23May 18May 14May 11May 9May 6May 4May 1Apr 26
24°FMay 15May 9May 6May 3Apr 30Apr 27Apr 24Apr 19Apr 14
20°FMay 6May 2Apr 29Apr 24Apr 20Apr 17Apr 13Apr 9Apr 5
16°FApr 30Apr 23Apr 18Apr 15Apr 11Apr 8Apr 5Apr 2Mar 28

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

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°F1271211171141101061039892
32°F142138133130127124120117111
28°F161155151147143140136131125
24°F184177171167163158153147141
20°F202195190185181176172166159
16°F220213208203199195190185177

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
9,939
Cooling degree days, base 65°F
249
Growing degree days, base 40°F
3,391
Growing degree days, base 45°F
2,515
Growing degree days, base 50°F
1,751
Growing degree days, base 55°F
1,109
Growing degree days, base 60°F
599

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,78700
February1,51700
March1,30501
April791018
May4237142
June13740357
July4997513
August7488480
September30117208
October739132
November1,19102
December1,62600

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 0.4 km from Mohall. 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 USC00326025 (Mohall). Public domain.