Lyons climate

Lyons Frost Dates and Growing Season

NOAA 1991-2020 normals for Morenci, 12.3 km from Lyons, elevation 770 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Morenci. 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 4 and the first fall freeze around October 7, a growing season of about 156 days.

Median at 36°F
last May 14, first September 28
Median at 32°F
last May 4, first October 7
Median at 28°F
last April 25, first October 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°FMay 30May 25May 21May 17May 14May 11May 8May 5May 1
32°FMay 19May 14May 9May 7May 4May 2Apr 30Apr 26Apr 22
28°FMay 9May 4May 1Apr 29Apr 25Apr 22Apr 20Apr 17Apr 13
24°FMay 1Apr 24Apr 20Apr 17Apr 15Apr 12Apr 9Apr 5Apr 1
20°FApr 16Apr 12Apr 8Apr 5Apr 2Mar 31Mar 28Mar 23Mar 17
16°FApr 7Apr 2Mar 30Mar 27Mar 23Mar 19Mar 15Mar 11Mar 7

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 15Sep 19Sep 23Sep 26Sep 28Oct 1Oct 3Oct 6Oct 10
32°FSep 24Sep 29Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20
28°FOct 4Oct 10Oct 13Oct 16Oct 20Oct 22Oct 25Oct 28Nov 1
24°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 15
20°FNov 1Nov 3Nov 6Nov 10Nov 13Nov 16Nov 19Nov 23Nov 29
16°FNov 8Nov 13Nov 18Nov 21Nov 25Nov 28Dec 1Dec 5Dec 11

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°F155148143139135132128124117
32°F174169164159156152148142134
28°F197191186182178174170163156
24°F222215209206202197193188180
20°F247239234229224221216211205
16°F270262256252247242237231224

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
6,637
Cooling degree days, base 65°F
626
Growing degree days, base 40°F
4,781
Growing degree days, base 45°F
3,688
Growing degree days, base 50°F
2,727
Growing degree days, base 55°F
1,897
Growing degree days, base 60°F
1,188

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27701
February1,09601
March921117
April547270
May23037293
June38143555
July8217674
August17164612
September13456377
October4615113
November788014
December1,12102

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 12.3 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 USC00205603 (Morenci). Public domain.