Wellston climate

Wellston Frost Dates and Growing Season

NOAA 1991-2020 normals for St Louis Sci Ctr, 5.3 km from Wellston, elevation 515 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for St Louis Sci Ctr. 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 1 and the first fall freeze around November 4, a growing season of about 218 days.

Median at 36°F
last April 12, first October 26
Median at 32°F
last April 1, first November 4
Median at 28°F
last March 22, first November 15

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 27Apr 22Apr 19Apr 16Apr 12Apr 9Apr 5Apr 2Mar 27
32°FApr 18Apr 11Apr 7Apr 4Apr 1Mar 29Mar 26Mar 21Mar 14
28°FApr 7Apr 3Mar 30Mar 26Mar 22Mar 18Mar 15Mar 10Mar 5
24°FMar 29Mar 22Mar 17Mar 14Mar 11Mar 7Mar 4Feb 28Feb 22
20°FMar 18Mar 13Mar 8Mar 5Mar 2Feb 28Feb 24Feb 18Feb 11
16°FMar 11Mar 5Mar 2Feb 28Feb 23Feb 18Feb 13Feb 6Jan 31

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 15Oct 18Oct 21Oct 24Oct 26Oct 29Oct 31Nov 2Nov 7
32°FOct 24Oct 28Oct 31Nov 2Nov 4Nov 7Nov 10Nov 14Nov 21
28°FNov 2Nov 5Nov 8Nov 12Nov 15Nov 19Nov 23Nov 28Dec 4
24°FNov 9Nov 14Nov 18Nov 22Nov 26Dec 1Dec 4Dec 8Dec 15
20°FNov 19Nov 25Nov 30Dec 3Dec 6Dec 12Dec 16Dec 21Dec 28
16°FNov 28Dec 3Dec 8Dec 14Dec 19Dec 23Dec 28Jan 1Jan 11

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°F216210206201197193190184178
32°F240232226223218215210205198
28°F264256249244239235230224217
24°F284276270265261255250244237
20°F305296290284279274268263253
16°F328316309304299294288281272

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
4,292
Cooling degree days, base 65°F
1,769
Growing degree days, base 40°F
7,323
Growing degree days, base 45°F
5,945
Growing degree days, base 50°F
4,703
Growing degree days, base 55°F
3,591
Growing degree days, base 60°F
2,611

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00409
February776023
March5659102
April25541275
May66157557
June5356801
July0484949
August1441905
September28226648
October21152326
November527592
December854016

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 5.3 km from Wellston. 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 USC00237452 (St Louis Sci Ctr). Public domain.