Smithville climate

Smithville Frost Dates and Growing Season

NOAA 1991-2020 normals for Wooster Wayne CO AP, 2.4 km from Smithville, elevation 1137 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wooster Wayne CO AP. 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 29 and the first fall freeze around October 14, a growing season of about 167 days.

Median at 36°F
last May 8, first October 1
Median at 32°F
last April 29, first October 14
Median at 28°F
last April 18, first October 28

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 24May 19May 15May 11May 8May 5May 2Apr 29Apr 24
32°FMay 15May 9May 4May 1Apr 29Apr 26Apr 23Apr 20Apr 15
28°FMay 1Apr 27Apr 23Apr 20Apr 18Apr 15Apr 11Apr 7Apr 2
24°FApr 19Apr 14Apr 10Apr 7Apr 4Apr 2Mar 30Mar 25Mar 19
20°FApr 7Apr 3Mar 31Mar 29Mar 24Mar 22Mar 18Mar 13Mar 8
16°FMar 30Mar 25Mar 21Mar 18Mar 14Mar 11Mar 8Mar 4Feb 28

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 19Sep 23Sep 27Sep 30Oct 1Oct 4Oct 7Oct 11Oct 14
32°FSep 29Oct 3Oct 7Oct 10Oct 14Oct 17Oct 20Oct 24Oct 29
28°FOct 10Oct 17Oct 21Oct 24Oct 28Oct 31Nov 2Nov 5Nov 10
24°FOct 23Oct 31Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 25
20°FNov 6Nov 11Nov 14Nov 17Nov 21Nov 25Nov 28Dec 2Dec 9
16°FNov 15Nov 21Nov 26Nov 30Dec 2Dec 6Dec 10Dec 16Dec 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°F164157152149145142137132126
32°F186180175171167163158153146
28°F214207202197193189183177170
24°F241233227223219215210205197
20°F266259252248243238234228221
16°F289279273268263259254248241

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
6,193
Cooling degree days, base 65°F
591
Growing degree days, base 40°F
4,949
Growing degree days, base 45°F
3,791
Growing degree days, base 50°F
2,775
Growing degree days, base 55°F
1,900
Growing degree days, base 60°F
1,165

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21002
February1,02603
March862124
April490499
May21241310
June42135543
July7207665
August19146592
September12749376
October4198136
November735022
December1,04304

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 2.4 km from Smithville. 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 USW00004842 (Wooster Wayne CO AP). Public domain.