Fairfield climate

Fairfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairfield, 0.5 km from Fairfield, elevation 3983 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 May 13 and the first fall freeze around September 27, a growing season of about 135 days.

Median at 36°F
last May 31, first September 15
Median at 32°F
last May 13, first September 27
Median at 28°F
last April 30, first October 7

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 14Jun 10Jun 5Jun 2May 31May 28May 24May 19May 14
32°FJun 1May 25May 20May 16May 13May 10May 6May 3Apr 28
28°FMay 14May 9May 5May 2Apr 30Apr 28Apr 24Apr 20Apr 14
24°FMay 4Apr 29Apr 25Apr 21Apr 18Apr 15Apr 11Apr 6Apr 2
20°FApr 27Apr 20Apr 16Apr 12Apr 9Apr 5Apr 2Mar 29Mar 21
16°FApr 17Apr 12Apr 7Apr 3Apr 1Mar 28Mar 22Mar 17Mar 9

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 1Sep 6Sep 10Sep 13Sep 15Sep 18Sep 21Sep 24Sep 29
32°FSep 14Sep 18Sep 21Sep 24Sep 27Sep 29Oct 1Oct 5Oct 9
28°FSep 24Sep 29Oct 1Oct 4Oct 7Oct 9Oct 13Oct 17Oct 23
24°FOct 1Oct 6Oct 9Oct 14Oct 17Oct 21Oct 25Oct 28Nov 2
20°FOct 6Oct 14Oct 19Oct 23Oct 26Oct 29Nov 2Nov 6Nov 13
16°FOct 15Oct 22Oct 26Oct 29Nov 2Nov 6Nov 10Nov 15Nov 22

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°F128122116112108104999386
32°F155148143139135131127122115
28°F183176169164160155151146138
24°F204196190186181176171165157
20°F224215210205200195189183174
16°F244235228221216211206200190

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
7,742
Cooling degree days, base 65°F
256
Growing degree days, base 40°F
3,572
Growing degree days, base 45°F
2,556
Growing degree days, base 50°F
1,732
Growing degree days, base 55°F
1,077
Growing degree days, base 60°F
586

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20601
February1,07101
March95006
April686027
May4245133
June21320268
July63109512
August8397483
September28522232
October634261
November93607
December1,19000

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.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00242857 (Fairfield). Public domain.