Galena climate

Galena Frost Dates and Growing Season

NOAA 1991-2020 normals for Galena, 4 km from Galena, elevation 822 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Galena. 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 26 and the first fall freeze around October 15, a growing season of about 170 days.

Median at 36°F
last May 6, first October 4
Median at 32°F
last April 26, first October 15
Median at 28°F
last April 14, 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 21May 15May 11May 8May 6May 3May 1Apr 28Apr 23
32°FMay 11May 6May 2Apr 29Apr 26Apr 23Apr 19Apr 16Apr 11
28°FMay 2Apr 26Apr 21Apr 18Apr 14Apr 11Apr 8Apr 5Apr 1
24°FApr 21Apr 14Apr 9Apr 6Apr 3Apr 1Mar 30Mar 24Mar 18
20°FApr 7Apr 2Mar 31Mar 28Mar 24Mar 20Mar 17Mar 13Mar 8
16°FMar 30Mar 25Mar 21Mar 18Mar 15Mar 13Mar 9Mar 5Mar 1

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 22Sep 26Sep 29Oct 2Oct 4Oct 6Oct 10Oct 12Oct 17
32°FOct 1Oct 5Oct 10Oct 12Oct 15Oct 17Oct 20Oct 23Oct 28
28°FOct 10Oct 16Oct 20Oct 23Oct 25Oct 28Oct 30Nov 1Nov 8
24°FOct 23Oct 28Oct 31Nov 1Nov 5Nov 8Nov 12Nov 15Nov 22
20°FNov 2Nov 6Nov 10Nov 13Nov 16Nov 20Nov 23Nov 26Dec 1
16°FNov 9Nov 15Nov 18Nov 22Nov 24Nov 27Dec 1Dec 4Dec 10

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°F168162157153150146142138132
32°F190183178174170166162157150
28°F213205201196193189184179173
24°F237230224220216211206200193
20°F260252246242237233228223216
16°F278270265260256251246242233

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
7,134
Cooling degree days, base 65°F
615
Growing degree days, base 40°F
4,744
Growing degree days, base 45°F
3,668
Growing degree days, base 50°F
2,721
Growing degree days, base 55°F
1,896
Growing degree days, base 60°F
1,184

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,44300
February1,19000
March948123
April548272
May24129277
June33130548
July7219677
August17168617
September14160376
October4686118
November851013
December1,24900

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 4 km from Galena. 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 USC00113312 (Galena). Public domain.