Cannon Ball climate

Cannon Ball Frost Dates and Growing Season

NOAA 1991-2020 normals for Hazelton 4NW, 23.9 km from Cannon Ball, elevation 1982 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hazelton 4NW. 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 12 and the first fall freeze around September 27, a growing season of about 136 days.

Median at 36°F
last May 22, first September 19
Median at 32°F
last May 12, first September 27
Median at 28°F
last May 4, first October 6

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

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

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°F135129125121118115111107100
32°F154148144139136132129125119
28°F172166161157154150146141134
24°F192186181176172168164159152
20°F210202197194189186181176169
16°F228221215211207203199194187

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
9,084
Cooling degree days, base 65°F
375
Growing degree days, base 40°F
3,779
Growing degree days, base 45°F
2,852
Growing degree days, base 50°F
2,039
Growing degree days, base 55°F
1,351
Growing degree days, base 60°F
788

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,67500
February1,40300
March1,18103
April731027
May37211173
June11260400
July32148581
August56121531
September24433268
October672254
November1,10303
December1,50300

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 23.9 km from Cannon Ball. 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 USC00324083 (Hazelton 4NW). Public domain.