Clark County climate

Clark County Frost Dates and Growing Season

NOAA 1991-2020 normals for Springfield Wtp, 6.6 km from Clark County, elevation 951 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Springfield Wtp. 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 25 and the first fall freeze around October 19, a growing season of about 175 days.

Median at 36°F
last May 5, first October 6
Median at 32°F
last April 25, first October 19
Median at 28°F
last April 15, first October 30

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 20May 15May 10May 8May 5May 1Apr 29Apr 26Apr 22
32°FMay 12May 6May 2Apr 29Apr 25Apr 23Apr 20Apr 17Apr 12
28°FApr 30Apr 25Apr 21Apr 18Apr 15Apr 12Apr 9Apr 5Mar 31
24°FApr 19Apr 14Apr 9Apr 5Apr 3Mar 31Mar 29Mar 24Mar 19
20°FApr 9Apr 2Mar 31Mar 28Mar 25Mar 21Mar 18Mar 14Mar 6
16°FMar 30Mar 24Mar 21Mar 17Mar 14Mar 11Mar 7Mar 3Feb 25

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 23Sep 29Oct 1Oct 4Oct 6Oct 9Oct 12Oct 15Oct 20
32°FOct 4Oct 9Oct 13Oct 16Oct 19Oct 21Oct 24Oct 27Nov 1
28°FOct 16Oct 20Oct 24Oct 27Oct 30Nov 1Nov 2Nov 5Nov 10
24°FOct 27Nov 1Nov 2Nov 4Nov 7Nov 11Nov 14Nov 18Nov 24
20°FNov 5Nov 10Nov 14Nov 17Nov 20Nov 24Nov 28Dec 2Dec 8
16°FNov 13Nov 19Nov 25Nov 29Dec 1Dec 5Dec 10Dec 17Dec 23

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°F172165160156153149145140133
32°F194188183178175171166160151
28°F214209204200197193189183177
24°F241233228223219215211206199
20°F268258252246241237231225218
16°F290281276270266260253246236

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
5,808
Cooling degree days, base 65°F
802
Growing degree days, base 40°F
5,414
Growing degree days, base 45°F
4,216
Growing degree days, base 50°F
3,154
Growing degree days, base 55°F
2,230
Growing degree days, base 60°F
1,443

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,17203
February98404
March807135
April4457127
May18258353
June28177600
July5248708
August8208665
September9290451
October37512168
November702034
December1,00906

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 6.6 km from Clark 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 USC00337935 (Springfield Wtp). Public domain.