Fairfield climate

Fairfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairfield RS, 0.5 km from Fairfield, elevation 5065 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairfield RS. 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 8 and the first fall freeze around September 14, a growing season of about 97 days.

Median at 32°F
last June 8, first September 14
Median at 28°F
last May 11, first September 28

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 28Jun 22Jun 17Jun 12Jun 8Jun 4May 30May 23May 15
28°FJun 7May 28May 20May 15May 11May 7May 3Apr 30Apr 24
24°FMay 10May 3Apr 30Apr 26Apr 22Apr 18Apr 14Apr 11Apr 5
20°FApr 24Apr 18Apr 13Apr 10Apr 7Apr 4Apr 2Mar 31Mar 24
16°FApr 10Apr 5Apr 2Mar 31Mar 28Mar 24Mar 20Mar 15Mar 10

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°FAug 29Sep 4Sep 7Sep 10Sep 14Sep 18Sep 21Sep 24Sep 28
28°FSep 9Sep 15Sep 20Sep 24Sep 28Sep 30Oct 3Oct 6Oct 11
24°FSep 22Sep 28Oct 2Oct 5Oct 8Oct 12Oct 14Oct 18Oct 24
20°FOct 3Oct 8Oct 14Oct 17Oct 21Oct 24Oct 27Oct 31Nov 5
16°FOct 15Oct 21Oct 25Oct 29Nov 1Nov 4Nov 9Nov 13Nov 19

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°F908278736964585143
32°F1231141081039792867970
28°F160151145140134129122115105
24°F190181176171167161155150142
20°F218210205200196191186180172
16°F242235229224219215210205198

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
8,520
Cooling degree days, base 65°F
216
Growing degree days, base 40°F
3,374
Growing degree days, base 45°F
2,441
Growing degree days, base 50°F
1,663
Growing degree days, base 55°F
1,025
Growing degree days, base 60°F
540

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,44900
February1,21800
March1,06500
April692017
May4261110
June22216258
July47110529
August6279483
September26010226
October634039
November1,02000
December1,42600

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 0.5 km from Fairfield. 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 USC00103108 (Fairfield RS). Public domain.