Fairfield climate

Fairfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairfield Radio Wfiw, 2.9 km from Fairfield, elevation 430 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairfield Radio Wfiw. 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 7 and the first fall freeze around October 26, a growing season of about 201 days.

Median at 36°F
last April 19, first October 17
Median at 32°F
last April 7, first October 26
Median at 28°F
last March 27, first November 6

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 1Apr 26Apr 23Apr 19Apr 17Apr 13Apr 9Apr 4
32°FApr 23Apr 18Apr 13Apr 10Apr 7Apr 3Apr 1Mar 29Mar 23
28°FApr 11Apr 5Apr 2Mar 30Mar 27Mar 24Mar 21Mar 17Mar 11
24°FMar 31Mar 27Mar 22Mar 18Mar 15Mar 12Mar 9Mar 5Feb 28
20°FMar 21Mar 16Mar 13Mar 9Mar 5Mar 2Feb 27Feb 22Feb 14
16°FMar 16Mar 9Mar 5Mar 1Feb 26Feb 20Feb 14Feb 8Feb 2

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°FOct 3Oct 9Oct 12Oct 15Oct 17Oct 19Oct 22Oct 25Oct 29
32°FOct 14Oct 19Oct 22Oct 24Oct 26Oct 29Oct 31Nov 4Nov 9
28°FOct 24Oct 30Nov 1Nov 4Nov 6Nov 8Nov 12Nov 16Nov 22
24°FNov 3Nov 7Nov 10Nov 14Nov 17Nov 21Nov 25Nov 30Dec 4
20°FNov 9Nov 15Nov 20Nov 24Nov 28Dec 1Dec 5Dec 10Dec 17
16°FNov 17Nov 25Dec 1Dec 4Dec 9Dec 14Dec 18Dec 23Jan 1

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°F199193187183179174170164155
32°F220214209205201197192187179
28°F245237233228224219215210203
24°F271263256251246242236230224
20°F295285278272266261257250243
16°F318308301294288282276268258

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
4,398
Cooling degree days, base 65°F
1,546
Growing degree days, base 40°F
7,001
Growing degree days, base 45°F
5,636
Growing degree days, base 50°F
4,412
Growing degree days, base 55°F
3,324
Growing degree days, base 60°F
2,366

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January99809
February779019
March575691
April25134269
May76138528
June5323768
July0425890
August1379843
September38196608
October23844297
November567375
December871015

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 2.9 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 USC00112931 (Fairfield Radio Wfiw). Public domain.