Cedar Valley climate

Cedar Valley Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairfield, 7.9 km from Cedar Valley, elevation 4880 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairfield. 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 June 2 and the first fall freeze around September 16, a growing season of about 103 days.

Median at 32°F
last June 2, first September 16
Median at 28°F
last May 19, first September 26

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°F–––––––––
32°FJun 24Jun 17Jun 11Jun 7Jun 2May 31May 28May 23May 18
28°FJun 10Jun 1May 27May 23May 19May 15May 12May 8May 2
24°FMay 26May 18May 12May 8May 4Apr 30Apr 27Apr 23Apr 17
20°FMay 8May 2Apr 27Apr 23Apr 19Apr 15Apr 11Apr 6Mar 30
16°FApr 23Apr 14Apr 8Apr 3Mar 30Mar 25Mar 19Mar 12Mar 6

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°F–––––––––
32°FSep 1Sep 6Sep 10Sep 13Sep 16Sep 18Sep 21Sep 24Sep 29
28°FSep 10Sep 17Sep 20Sep 23Sep 26Sep 29Oct 1Oct 3Oct 7
24°FSep 23Sep 28Oct 1Oct 3Oct 5Oct 7Oct 10Oct 15Oct 19
20°FOct 1Oct 5Oct 9Oct 12Oct 16Oct 19Oct 22Oct 26Oct 30
16°FOct 11Oct 18Oct 21Oct 25Oct 28Nov 1Nov 2Nov 6Nov 12

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°F999286817672666151
32°F12511811210710398938676
28°F150143137132127122117111101
24°F174166161156152148143137127
20°F204195189183179173169163154
16°F239229221215210204198191181

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
6,713
Cooling degree days, base 65°F
406
Growing degree days, base 40°F
4,225
Growing degree days, base 45°F
3,129
Growing degree days, base 50°F
2,217
Growing degree days, base 55°F
1,468
Growing degree days, base 60°F
863

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20000
February95000
March76306
April561038
May3314174
June10854398
July9183638
August17140589
September17025314
October541056
November87603
December1,18700

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 7.9 km from Cedar Valley. 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 USC00422696 (Fairfield). Public domain.