Jackman climate

Jackman Frost Dates and Growing Season

NOAA 1991-2020 normals for Jackman, 0.7 km from Jackman, elevation 1214 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Jackman. 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 26 and the first fall freeze around September 23, a growing season of about 119 days.

Median at 36°F
last June 7, first September 8
Median at 32°F
last May 26, first September 23
Median at 28°F
last May 11, first October 3

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

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

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°F112105101979388847969
32°F14013312712311911511110699
28°F163156152148143140135130122
24°F187180174171167162157153147
20°F209203198194191187182177168
16°F229223219215212209205201194

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
9,508
Cooling degree days, base 65°F
156
Growing degree days, base 40°F
3,115
Growing degree days, base 45°F
2,248
Growing degree days, base 50°F
1,507
Growing degree days, base 55°F
896
Growing degree days, base 60°F
437

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,66800
February1,45500
March1,30501
April85706
May471499
June18528299
July7367459
August9544414
September29613199
October678028
November1,00402
December1,42300

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 0.7 km from Jackman. 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 USC00174086 (Jackman). Public domain.