Elsah climate

Elsah Frost Dates and Growing Season

NOAA 1991-2020 normals for St Charles CO AP, 6.6 km from Elsah, elevation 436 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for St Charles CO AP. 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 5 and the first fall freeze around October 27, a growing season of about 203 days.

Median at 36°F
last April 17, first October 17
Median at 32°F
last April 5, first October 27
Median at 28°F
last March 26, first November 6

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

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 1Oct 6Oct 11Oct 14Oct 17Oct 19Oct 22Oct 25Oct 29
32°FOct 13Oct 18Oct 22Oct 24Oct 27Oct 30Nov 1Nov 3Nov 9
28°FOct 26Oct 31Nov 1Nov 4Nov 6Nov 9Nov 13Nov 18Nov 24
24°FNov 3Nov 6Nov 9Nov 13Nov 17Nov 21Nov 25Nov 30Dec 7
20°FNov 10Nov 17Nov 21Nov 25Nov 30Dec 2Dec 6Dec 11Dec 19
16°FNov 21Nov 27Dec 2Dec 6Dec 11Dec 15Dec 20Dec 24Dec 30

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°F200193188184181177173168162
32°F222215211207203199195191185
28°F248240235231226221217212205
24°F270262256252247242237231223
20°F292283276271267262256251243
16°F316306299293288282275269259

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
4,681
Cooling degree days, base 65°F
1,465
Growing degree days, base 40°F
6,738
Growing degree days, base 45°F
5,413
Growing degree days, base 50°F
4,230
Growing degree days, base 55°F
3,178
Growing degree days, base 60°F
2,255

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06004
February830012
March611472
April27625240
May77127515
June5317762
July0422887
August1370834
September41166575
October26534265
November601156
December913010

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 6.6 km from Elsah. 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 USW00053904 (St Charles CO AP). Public domain.