Galena climate

Galena Frost Dates and Growing Season

NOAA 1991-2020 normals for Louisville Mcalpine, 15.5 km from Galena, elevation 440 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Louisville Mcalpine. 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 March 31 and the first fall freeze around November 9, a growing season of about 225 days.

Median at 36°F
last April 11, first November 1
Median at 32°F
last March 31, first November 9
Median at 28°F
last March 18, first November 20

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

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°F223216211207203199195190181
32°F245238233229225220215211204
28°F271262256251246242237232226
24°F297288281275270265259253244
20°F323313306300295289283276267
16°F344334328322317309304297287

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
98% 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
4,141
Cooling degree days, base 65°F
1,642
Growing degree days, base 40°F
7,222
Growing degree days, base 45°F
5,818
Growing degree days, base 50°F
4,560
Growing degree days, base 55°F
3,456
Growing degree days, base 60°F
2,482

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January94208
February745018
March577791
April23930277
May73155549
June2320768
July0443908
August1416880
September22222649
October20146323
November532471
December808018

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 15.5 km from Galena. 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 USC00154955 (Louisville Mcalpine). Public domain.