Olney climate

Olney Frost Dates and Growing Season

NOAA 1991-2020 normals for Olney 2S, 3.4 km from Olney, elevation 459 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Olney 2S. 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 15 and the first fall freeze around October 23, a growing season of about 189 days.

Median at 36°F
last April 26, first October 13
Median at 32°F
last April 15, first October 23
Median at 28°F
last April 3, first November 1

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 13May 7May 2Apr 30Apr 26Apr 23Apr 19Apr 16Apr 11
32°FMay 3Apr 26Apr 22Apr 18Apr 15Apr 11Apr 8Apr 5Apr 1
28°FApr 18Apr 13Apr 9Apr 6Apr 3Apr 1Mar 30Mar 25Mar 19
24°FApr 8Apr 3Apr 1Mar 29Mar 26Mar 22Mar 18Mar 14Mar 6
20°FMar 31Mar 26Mar 21Mar 18Mar 13Mar 10Mar 4Feb 28Feb 22
16°FMar 21Mar 15Mar 11Mar 7Mar 3Feb 28Feb 22Feb 16Feb 8

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 7Oct 10Oct 13Oct 15Oct 19Oct 22Oct 26
32°FOct 8Oct 13Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 3
28°FOct 17Oct 23Oct 26Oct 29Nov 1Nov 2Nov 5Nov 9Nov 15
24°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 23Nov 29
20°FNov 4Nov 9Nov 13Nov 16Nov 20Nov 25Nov 30Dec 3Dec 11
16°FNov 12Nov 19Nov 24Nov 29Dec 2Dec 6Dec 11Dec 17Dec 25

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°F188181176172168164159153146
32°F210202198193189186181176169
28°F233225220215211207203198190
24°F258250243239233228223217209
20°F281273267260255250244238229
16°F306297289284277272266259249

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
5,102
Cooling degree days, base 65°F
1,195
Growing degree days, base 40°F
6,244
Growing degree days, base 45°F
4,969
Growing degree days, base 50°F
3,829
Growing degree days, base 55°F
2,818
Growing degree days, base 60°F
1,939

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,10605
February88808
March690357
April34015191
May11792444
June10257697
July1348812
August2305769
September53146544
October29428240
November640253
December96109

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 3.4 km from Olney. 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 USC00116446 (Olney 2S). Public domain.