Clinton climate

Clinton Frost Dates and Growing Season

NOAA 1991-2020 normals for Union City, 30.7 km from Clinton, elevation 350 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Union City. 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 3 and the first fall freeze around October 29, a growing season of about 208 days.

Median at 36°F
last April 15, first October 19
Median at 32°F
last April 3, first October 29
Median at 28°F
last March 22, first November 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°FApr 28Apr 24Apr 20Apr 17Apr 15Apr 12Apr 8Apr 4Mar 30
32°FApr 19Apr 14Apr 10Apr 6Apr 3Mar 31Mar 28Mar 24Mar 18
28°FApr 8Apr 3Mar 31Mar 26Mar 22Mar 19Mar 16Mar 11Mar 4
24°FMar 28Mar 21Mar 17Mar 13Mar 8Mar 5Mar 1Feb 26Feb 18
20°FMar 17Mar 11Mar 6Mar 2Feb 27Feb 22Feb 16Feb 9Feb 2
16°FMar 7Feb 28Feb 24Feb 17Feb 12Feb 5Feb 1Jan 24Jan 14

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 7Oct 12Oct 14Oct 17Oct 19Oct 21Oct 23Oct 26Oct 30
32°FOct 17Oct 20Oct 24Oct 26Oct 29Oct 31Nov 2Nov 5Nov 10
28°FOct 26Oct 30Nov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 26
24°FNov 3Nov 7Nov 12Nov 16Nov 20Nov 24Nov 30Dec 3Dec 10
20°FNov 13Nov 20Nov 26Dec 1Dec 3Dec 8Dec 15Dec 23Dec 30
16°FNov 28Dec 3Dec 10Dec 17Dec 24Dec 29Jan 1Jan 7Jan 18

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°F208201197193189185181175169
32°F230222217212208204199195188
28°F256248241236230225221216209
24°F285274267261255251245239230
20°F317305297290283276270262253
16°F346334326319313306298289277

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
98% 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
4,060
Cooling degree days, base 65°F
1,526
Growing degree days, base 40°F
7,143
Growing degree days, base 45°F
5,730
Growing degree days, base 50°F
4,461
Growing degree days, base 55°F
3,337
Growing degree days, base 60°F
2,359

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January908016
February717024
March532598
April24330269
May60144549
June2326774
July0418883
August1369834
September31190609
October23040298
November531385
December806022

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 30.7 km from Clinton. 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 USC00409219 (Union City). Public domain.