Logan climate

Logan Frost Dates and Growing Season

NOAA 1991-2020 normals for Norton 9SSE, 24.4 km from Logan, elevation 2413 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Norton 9SSE. 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 April 27 and the first fall freeze around October 17, a growing season of about 173 days.

Median at 36°F
last May 5, first October 7
Median at 32°F
last April 27, first October 17
Median at 28°F
last April 15, first October 25

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

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°F171165161157154149145141134
32°F191184180175173168164159151
28°F212205200196192187183179172
24°F232225220215210206201196189
20°F250242237232228223218212204
16°F272263256251246241235230220

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
5,548
Cooling degree days, base 65°F
1,204
Growing degree days, base 40°F
5,995
Growing degree days, base 45°F
4,756
Growing degree days, base 50°F
3,663
Growing degree days, base 55°F
2,706
Growing degree days, base 60°F
1,885

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11702
February91807
March712147
April4247135
May17761364
June19239671
July1398862
August4337798
September73142523
October34220214
November708039
December1,05202

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 24.4 km from Logan. 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 USC00145856 (Norton 9SSE). Public domain.