Lyons climate

Lyons Frost Dates and Growing Season

NOAA 1991-2020 normals for Sterling, 14.5 km from Lyons, elevation 1636 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sterling. 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 15 and the first fall freeze around October 23, a growing season of about 190 days.

Median at 36°F
last April 26, first October 15
Median at 32°F
last April 15, first October 23
Median at 28°F
last April 6, first November 1

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 6May 2Apr 30Apr 28Apr 26Apr 23Apr 20Apr 17Apr 13
32°FApr 30Apr 26Apr 22Apr 18Apr 15Apr 12Apr 10Apr 7Apr 2
28°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 3Apr 1Mar 28Mar 22
24°FApr 10Apr 5Apr 2Mar 31Mar 27Mar 23Mar 19Mar 14Mar 9
20°FApr 3Mar 29Mar 23Mar 19Mar 16Mar 12Mar 8Mar 4Feb 28
16°FMar 23Mar 17Mar 12Mar 8Mar 5Mar 2Feb 28Feb 23Feb 17

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 30Oct 4Oct 8Oct 12Oct 15Oct 17Oct 20Oct 22Oct 25
32°FOct 7Oct 15Oct 19Oct 21Oct 23Oct 25Oct 28Nov 1Nov 4
28°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 4Nov 7Nov 10Nov 15
24°FOct 27Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 20Nov 26
20°FNov 2Nov 8Nov 12Nov 16Nov 19Nov 23Nov 26Dec 1Dec 6
16°FNov 11Nov 17Nov 23Nov 26Nov 30Dec 2Dec 6Dec 12Dec 18

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°F190183178175171167164159152
32°F209203198194190185181177169
28°F228222216213209205201196189
24°F250242237232227222217213205
20°F271263258252247242236231222
16°F295287280274270264258251242

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
5,028
Cooling degree days, base 65°F
1,585
Growing degree days, base 40°F
6,664
Growing degree days, base 45°F
5,375
Growing degree days, base 50°F
4,230
Growing degree days, base 55°F
3,219
Growing degree days, base 60°F
2,338

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06302
February86109
March651261
April35215184
May114111467
June7329772
July1484948
August2415879
September49198600
October28731257
November649149
December99303

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 14.5 km from Lyons. 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 USC00147796 (Sterling). Public domain.