Dixon County climate

Dixon County Frost Dates and Growing Season

NOAA 1991-2020 normals for Concord, 15.6 km from Dixon County, elevation 1444 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Concord. 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 2 and the first fall freeze around October 4, a growing season of about 154 days.

Median at 36°F
last May 10, first September 26
Median at 32°F
last May 2, first October 4
Median at 28°F
last April 23, first October 14

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 23May 19May 16May 13May 10May 8May 6May 3Apr 30
32°FMay 16May 10May 7May 5May 2Apr 30Apr 27Apr 23Apr 19
28°FMay 7May 2Apr 29Apr 26Apr 23Apr 20Apr 17Apr 13Apr 8
24°FApr 27Apr 22Apr 18Apr 15Apr 12Apr 10Apr 7Apr 4Mar 31
20°FApr 19Apr 14Apr 9Apr 7Apr 5Apr 2Mar 31Mar 26Mar 19
16°FApr 10Apr 6Apr 2Mar 31Mar 27Mar 22Mar 19Mar 14Mar 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°FSep 13Sep 18Sep 20Sep 23Sep 26Sep 29Oct 1Oct 4Oct 8
32°FSep 20Sep 25Sep 28Oct 1Oct 4Oct 6Oct 9Oct 13Oct 16
28°FSep 29Oct 4Oct 8Oct 11Oct 14Oct 17Oct 20Oct 22Oct 26
24°FOct 12Oct 16Oct 19Oct 22Oct 24Oct 26Oct 29Nov 1Nov 5
20°FOct 20Oct 24Oct 28Oct 31Nov 1Nov 4Nov 6Nov 10Nov 16
16°FOct 28Nov 2Nov 5Nov 7Nov 10Nov 12Nov 15Nov 19Nov 25

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°F155149145141138135130126120
32°F171165160157154150146141135
28°F191184180175172169165160152
24°F209204200196192188184179173
20°F230222218213210206202198191
16°F249241236232227223218213207

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
6,948
Cooling degree days, base 65°F
829
Growing degree days, base 40°F
5,067
Growing degree days, base 45°F
3,975
Growing degree days, base 50°F
3,006
Growing degree days, base 55°F
2,158
Growing degree days, base 60°F
1,435

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,39600
February1,15600
March895122
April523487
May22552319
June26179603
July6276734
August10230685
September12078413
October4579131
November866012
December1,26900

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 15.6 km from Dixon County. 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 USC00253652 (Concord). Public domain.