Oolitic climate

Oolitic Frost Dates and Growing Season

NOAA 1991-2020 normals for Oolitic Purdue Ex Fm, 2.8 km from Oolitic, elevation 652 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oolitic Purdue Ex Fm. 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 20 and the first fall freeze around October 20, a growing season of about 181 days.

Median at 36°F
last May 1, first October 10
Median at 32°F
last April 20, first October 20
Median at 28°F
last April 7, 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 18May 13May 8May 5May 1Apr 29Apr 24Apr 21Apr 16
32°FMay 7May 1Apr 28Apr 24Apr 20Apr 17Apr 14Apr 9Apr 6
28°FApr 25Apr 20Apr 15Apr 11Apr 7Apr 4Apr 2Mar 31Mar 24
24°FApr 11Apr 5Apr 2Mar 31Mar 28Mar 24Mar 21Mar 17Mar 10
20°FApr 1Mar 28Mar 23Mar 19Mar 16Mar 12Mar 8Mar 3Feb 26
16°FMar 22Mar 16Mar 11Mar 7Mar 4Mar 1Feb 26Feb 20Feb 11

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 29Oct 3Oct 6Oct 8Oct 10Oct 13Oct 16Oct 19Oct 22
32°FOct 6Oct 11Oct 14Oct 16Oct 20Oct 22Oct 24Oct 27Oct 30
28°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 12
24°FOct 28Nov 1Nov 2Nov 5Nov 9Nov 12Nov 16Nov 21Nov 28
20°FNov 5Nov 11Nov 15Nov 18Nov 22Nov 27Dec 1Dec 3Dec 10
16°FNov 14Nov 21Nov 26Dec 1Dec 3Dec 7Dec 12Dec 18Dec 24

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°F179173169165161157154149143
32°F200194189185181177173168160
28°F224216211206203198194188181
24°F251243237231227223218212203
20°F276268262257252247242236229
16°F301291285280274268263257249

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
5,311
Cooling degree days, base 65°F
969
Growing degree days, base 40°F
5,859
Growing degree days, base 45°F
4,601
Growing degree days, base 50°F
3,484
Growing degree days, base 55°F
2,506
Growing degree days, base 60°F
1,666

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11106
February90408
March716248
April37711164
May14468395
June17200633
July2292755
August4264725
September71117498
October33816196
November656147
December972010

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 2.8 km from Oolitic. 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 USC00126580 (Oolitic Purdue Ex Fm). Public domain.