Trempealeau climate

Trempealeau Frost Dates and Growing Season

NOAA 1991-2020 normals for Trempealeau Dam 6, 0.8 km from Trempealeau, elevation 660 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Trempealeau Dam 6. 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 29 and the first fall freeze around October 11, a growing season of about 165 days.

Median at 36°F
last May 8, first October 2
Median at 32°F
last April 29, first October 11
Median at 28°F
last April 17, first October 23

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 22May 17May 14May 11May 8May 5May 2Apr 29Apr 24
32°FMay 13May 8May 4May 1Apr 29Apr 26Apr 23Apr 18Apr 11
28°FMay 2Apr 29Apr 24Apr 20Apr 17Apr 12Apr 9Apr 6Apr 2
24°FApr 23Apr 17Apr 11Apr 8Apr 6Apr 4Apr 1Mar 30Mar 24
20°FApr 12Apr 7Apr 4Apr 2Mar 31Mar 28Mar 24Mar 19Mar 14
16°FApr 5Apr 1Mar 29Mar 26Mar 23Mar 19Mar 16Mar 13Mar 8

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 19Sep 23Sep 27Sep 30Oct 2Oct 4Oct 7Oct 10Oct 15
32°FSep 26Oct 2Oct 5Oct 8Oct 11Oct 14Oct 17Oct 21Oct 26
28°FOct 7Oct 13Oct 16Oct 20Oct 23Oct 26Oct 28Oct 31Nov 4
24°FOct 19Oct 25Oct 28Oct 31Nov 1Nov 4Nov 6Nov 10Nov 16
20°FOct 30Nov 2Nov 5Nov 7Nov 10Nov 14Nov 17Nov 21Nov 26
16°FNov 4Nov 8Nov 12Nov 16Nov 19Nov 22Nov 25Nov 28Dec 2

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°F165159154150147143139134128
32°F187180174170165161157152145
28°F209202197193188184180173166
24°F230222217212208204200193185
20°F248240234231227223219213206
16°F262256251246243239234229222

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
7,328
Cooling degree days, base 65°F
657
Growing degree days, base 40°F
4,752
Growing degree days, base 45°F
3,696
Growing degree days, base 50°F
2,751
Growing degree days, base 55°F
1,923
Growing degree days, base 60°F
1,222

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48900
February1,22800
March980011
April545376
May22635292
June37139552
July6234693
August16177626
September13762382
October4785109
November884012
December1,30200

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 0.8 km from Trempealeau. 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 USC00478589 (Trempealeau Dam 6). Public domain.