Oakley climate

Oakley Frost Dates and Growing Season

NOAA 1991-2020 normals for Oakley, 1.6 km from Oakley, elevation 4559 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oakley. 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 15 and the first fall freeze around October 2, a growing season of about 137 days.

Median at 36°F
last June 2, first September 22
Median at 32°F
last May 15, first October 2
Median at 28°F
last April 30, first October 16

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°FJun 19Jun 14Jun 10Jun 6Jun 2May 31May 26May 21May 16
32°FJun 6May 30May 23May 18May 15May 12May 8May 4Apr 30
28°FMay 15May 9May 6May 3Apr 30Apr 27Apr 24Apr 19Apr 13
24°FMay 4Apr 28Apr 22Apr 19Apr 14Apr 10Apr 5Mar 31Mar 22
20°FApr 22Apr 12Apr 5Apr 1Mar 27Mar 21Mar 15Mar 8Mar 2
16°FMar 28Mar 18Mar 12Mar 7Mar 3Feb 28Feb 23Feb 17Feb 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 5Sep 11Sep 16Sep 19Sep 22Sep 24Sep 27Oct 1Oct 6
32°FSep 16Sep 22Sep 26Sep 29Oct 2Oct 6Oct 10Oct 13Oct 17
28°FSep 30Oct 5Oct 9Oct 13Oct 16Oct 19Oct 23Oct 26Nov 1
24°FOct 13Oct 18Oct 21Oct 25Oct 28Oct 31Nov 3Nov 6Nov 14
20°FOct 22Oct 27Oct 31Nov 3Nov 6Nov 10Nov 14Nov 18Nov 24
16°FOct 29Nov 4Nov 10Nov 14Nov 18Nov 21Nov 24Nov 29Dec 5

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°F1341261201151101051009485
32°F161154149143137132127120111
28°F190183178174170164159153144
24°F222213208202197192187179171
20°F251241235229224218212204194
16°F284274267261255249243236225

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
6,115
Cooling degree days, base 65°F
529
Growing degree days, base 40°F
4,586
Growing degree days, base 45°F
3,422
Growing degree days, base 50°F
2,445
Growing degree days, base 55°F
1,648
Growing degree days, base 60°F
1,011

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06500
February85801
March719014
April536052
May3138195
June12060393
July16217666
August21193637
September14149366
October4512111
November792011
December1,08300

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 1.6 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 USC00106542 (Oakley). Public domain.