Hopkins climate

Hopkins Frost Dates and Growing Season

NOAA 1991-2020 normals for Allegan 5NE, 5.4 km from Hopkins, elevation 750 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Allegan 5NE. 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 4 and the first fall freeze around October 15, a growing season of about 160 days.

Median at 36°F
last May 17, first October 1
Median at 32°F
last May 4, first October 15
Median at 28°F
last April 24, first October 29

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

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 18Sep 23Sep 27Sep 29Oct 1Oct 5Oct 7Oct 10Oct 14
32°FSep 30Oct 4Oct 8Oct 12Oct 15Oct 18Oct 21Oct 24Oct 29
28°FOct 11Oct 18Oct 22Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
24°FOct 28Nov 1Nov 4Nov 7Nov 11Nov 14Nov 17Nov 22Nov 28
20°FNov 8Nov 13Nov 17Nov 20Nov 24Nov 28Dec 1Dec 4Dec 10
16°FNov 19Nov 24Nov 29Dec 1Dec 5Dec 8Dec 12Dec 17Dec 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°F159152148143138134130125118
32°F183175170165160156151146139
28°F208199194189184180176170163
24°F234226221216212207202197188
20°F260253247242238233229222214
16°F281274269264260255251245237

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
6,883
Cooling degree days, base 65°F
503
Growing degree days, base 40°F
4,520
Growing degree days, base 45°F
3,446
Growing degree days, base 50°F
2,506
Growing degree days, base 55°F
1,694
Growing degree days, base 60°F
1,020

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30300
February1,13600
March969011
April577468
May28529244
June62111499
July19168614
August21140584
September14846353
October4556115
November783015
December1,12502

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 5.4 km from Hopkins. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00200128 (Allegan 5NE). Public domain.