Merrillan climate

Merrillan Frost Dates and Growing Season

NOAA 1991-2020 normals for Neillsville 3ESE, 26.1 km from Merrillan, elevation 1080 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Neillsville 3ESE. 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 10 and the first fall freeze around October 1, a growing season of about 144 days.

Median at 36°F
last May 20, first September 23
Median at 32°F
last May 10, first October 1
Median at 28°F
last April 30, first October 10

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

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 9Sep 14Sep 17Sep 20Sep 23Sep 25Sep 28Oct 1Oct 4
32°FSep 18Sep 23Sep 26Sep 28Oct 1Oct 3Oct 5Oct 9Oct 14
28°FSep 26Sep 30Oct 3Oct 6Oct 10Oct 14Oct 17Oct 22Oct 26
24°FOct 5Oct 11Oct 17Oct 21Oct 24Oct 27Oct 30Nov 2Nov 9
20°FOct 20Oct 27Oct 30Nov 1Nov 3Nov 7Nov 11Nov 16Nov 21
16°FOct 30Nov 2Nov 6Nov 10Nov 14Nov 17Nov 20Nov 24Nov 28

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°F144138133128124121116112104
32°F161155151147144140135131123
28°F184177172167163159154149141
24°F210202197193187183177172164
20°F233225219214211206202196188
16°F250242236232227222218213207

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
8,143
Cooling degree days, base 65°F
396
Growing degree days, base 40°F
4,073
Growing degree days, base 45°F
3,083
Growing degree days, base 50°F
2,213
Growing degree days, base 55°F
1,466
Growing degree days, base 60°F
851

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,56700
February1,30300
March1,07309
April642145
May30619217
June7785459
July25149589
August47105524
September21233288
October565374
November95607
December1,37000

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 26.1 km from Merrillan. 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 USC00475808 (Neillsville 3ESE). Public domain.