Lemmon Valley climate

Lemmon Valley Frost Dates and Growing Season

NOAA 1991-2020 normals for Stead, 3.7 km from Lemmon Valley, elevation 5101 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stead. 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 May 8 and the first fall freeze around October 12, a growing season of about 150 days.

Median at 36°F
last June 1, first October 1
Median at 32°F
last May 8, first October 12
Median at 28°F
last April 23, first October 22

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°FJun 16Jun 11Jun 7Jun 4Jun 1May 28May 24May 18May 11
32°FJun 2May 26May 18May 13May 8May 4May 1Apr 27Apr 22
28°FMay 13May 4Apr 30Apr 26Apr 23Apr 20Apr 17Apr 13Apr 7
24°FApr 28Apr 21Apr 16Apr 12Apr 8Apr 4Apr 1Mar 26Mar 17
20°FApr 10Apr 2Mar 28Mar 21Mar 16Mar 10Mar 5Feb 28Feb 19
16°FMar 18Mar 9Mar 4Feb 28Feb 24Feb 17Feb 11Feb 4Jan 25

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 13Sep 20Sep 24Sep 27Oct 1Oct 3Oct 5Oct 9Oct 14
32°FSep 28Oct 1Oct 5Oct 8Oct 12Oct 15Oct 18Oct 22Oct 28
28°FOct 7Oct 13Oct 16Oct 19Oct 22Oct 25Oct 29Nov 2Nov 6
24°FOct 19Oct 23Oct 27Oct 30Nov 2Nov 5Nov 9Nov 12Nov 17
20°FOct 29Nov 2Nov 6Nov 10Nov 13Nov 16Nov 20Nov 24Nov 29
16°FNov 6Nov 12Nov 17Nov 21Nov 24Nov 28Dec 2Dec 6Dec 16

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°F144136132127122118113108100
32°F175168162156150145141135127
28°F205195190185181176172165157
24°F231223217211207202196191182
20°F271260251247240234227219209
16°F311299289281274268261253243

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
5,665
Cooling degree days, base 65°F
596
Growing degree days, base 40°F
4,821
Growing degree days, base 45°F
3,615
Growing degree days, base 50°F
2,609
Growing degree days, base 55°F
1,794
Growing degree days, base 60°F
1,131

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January97201
February79002
March705014
April537052
May30311209
June10376427
July7251708
August12193646
September10661410
October4154128
November737012
December97901

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 3.7 km from Lemmon Valley. 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 USC00267820 (Stead). Public domain.