Oak Glen climate

Oak Glen Frost Dates and Growing Season

NOAA 1991-2020 normals for Big Bear Lake, 21.7 km from Oak Glen, elevation 6753 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Big Bear Lake. 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 27 and the first fall freeze around October 4, a growing season of about 131 days.

Median at 36°F
last June 9, first September 20
Median at 32°F
last May 27, first October 4
Median at 28°F
last May 4, first October 20

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 29Jun 21Jun 16Jun 12Jun 9Jun 6Jun 4Jun 1May 27
32°FJun 9Jun 5Jun 2May 31May 27May 23May 18May 13May 6
28°FMay 27May 20May 15May 9May 4Apr 30Apr 28Apr 23Apr 17
24°FMay 1Apr 27Apr 23Apr 19Apr 15Apr 11Apr 7Apr 4Mar 28
20°FApr 18Apr 11Apr 6Apr 2Mar 29Mar 21Mar 15Mar 10Mar 3
16°FApr 4Mar 24Mar 16Mar 10Mar 6Mar 2Feb 26Feb 18Feb 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°FAug 31Sep 7Sep 13Sep 16Sep 20Sep 23Sep 26Sep 29Oct 4
32°FSep 21Sep 26Sep 29Oct 1Oct 4Oct 7Oct 10Oct 14Oct 20
28°FOct 4Oct 8Oct 13Oct 16Oct 20Oct 23Oct 28Nov 1Nov 4
24°FOct 17Oct 24Oct 29Nov 1Nov 4Nov 7Nov 11Nov 15Nov 20
20°FOct 31Nov 6Nov 11Nov 16Nov 20Nov 24Nov 27Dec 1Dec 6
16°FNov 15Nov 21Nov 25Nov 30Dec 3Dec 8Dec 13Dec 18Dec 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°F12411611110710197918474
32°F154146140135131126121115109
28°F192183177172167162157149141
24°F228219213208204198192187179
20°F264254246240233229223215206
16°F306293284275269262255247236

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
6,271
Cooling degree days, base 65°F
96
Growing degree days, base 40°F
3,691
Growing degree days, base 45°F
2,547
Growing degree days, base 50°F
1,644
Growing degree days, base 55°F
929
Growing degree days, base 60°F
396

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January93500
February84800
March80301
April626015
May4190112
June1798285
July5053468
August6032437
September1983261
October490062
November73103
December93500

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 21.7 km from Oak Glen. 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 USC00040741 (Big Bear Lake). Public domain.