Oakley climate

Oakley Frost Dates and Growing Season

NOAA 1991-2020 normals for Oakley 4W, 7.3 km from Oakley, elevation 3102 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oakley 4W. 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 May 6 and the first fall freeze around October 9, a growing season of about 156 days.

Median at 36°F
last May 14, first October 1
Median at 32°F
last May 6, first October 9
Median at 28°F
last April 27, first October 18

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

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 18Sep 23Sep 26Sep 28Oct 1Oct 3Oct 5Oct 8Oct 11
32°FSep 27Oct 1Oct 4Oct 6Oct 9Oct 11Oct 14Oct 17Oct 21
28°FOct 4Oct 9Oct 12Oct 15Oct 18Oct 21Oct 23Oct 25Oct 29
24°FOct 12Oct 18Oct 21Oct 24Oct 26Oct 29Oct 31Nov 2Nov 7
20°FOct 19Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17
16°FOct 26Nov 1Nov 4Nov 7Nov 11Nov 14Nov 18Nov 22Nov 28

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°F154149145142138134131127120
32°F173167163160156153149145137
28°F192185180176172168165161154
24°F211204199195190187183178171
20°F232224219215210207203197190
16°F253245239234229224219213204

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
5,879
Cooling degree days, base 65°F
1,066
Growing degree days, base 40°F
5,595
Growing degree days, base 45°F
4,405
Growing degree days, base 50°F
3,364
Growing degree days, base 55°F
2,465
Growing degree days, base 60°F
1,701

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11801
February93904
March757032
April4773104
May21446319
June29220642
July3366827
August6296755
September94123484
October39912169
November765024
December1,07901

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 7.3 km from Oakley. 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 USC00145888 (Oakley 4W). Public domain.