Rosamond climate

Rosamond Frost Dates and Growing Season

NOAA 1991-2020 normals for Lancaster Wm J Fox Fld, 14.4 km from Rosamond, elevation 2338 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lancaster Wm J Fox Fld. 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 3 and the first fall freeze around November 1, a growing season of about 211 days.

Median at 36°F
last April 19, first October 22
Median at 32°F
last April 3, first November 1
Median at 28°F
last March 8, first November 10

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 5Apr 30Apr 26Apr 22Apr 19Apr 15Apr 11Apr 6Mar 31
32°FApr 23Apr 17Apr 11Apr 6Apr 3Mar 29Mar 24Mar 18Mar 8
28°FApr 7Mar 30Mar 20Mar 14Mar 8Mar 3Feb 27Feb 22Feb 14
24°FMar 12Mar 4Feb 26Feb 22Feb 16Feb 10Feb 3Jan 28Jan 14
20°FFeb 22Feb 11Feb 3Jan 29Jan 21Jan 9Jan 1Dec 26Dec 14
16°FFeb 5Jan 27Jan 14Jan 6Dec 31Dec 27Dec 22Dec 15Dec 7

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°FOct 7Oct 12Oct 15Oct 19Oct 22Oct 24Oct 27Oct 31Nov 3
32°FOct 17Oct 22Oct 27Oct 30Nov 1Nov 4Nov 6Nov 9Nov 14
28°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 20Nov 26
24°FNov 4Nov 9Nov 13Nov 17Nov 20Nov 24Nov 28Dec 1Dec 8
20°FNov 15Nov 21Nov 26Nov 30Dec 3Dec 7Dec 12Dec 19Jan 1
16°FNov 28Dec 2Dec 8Dec 11Dec 17Dec 22Dec 30Jan 4Jan 19

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°F210201195189185180175170163
32°F240230223217211206200194185
28°F274264256249244239232225212
24°F316302293286279274268260249
20°F356342334329323314304293281
16°F365365365364355345339333322

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
94% of years
16°F or colder
65% 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
2,949
Cooling degree days, base 65°F
1,905
Growing degree days, base 40°F
8,137
Growing degree days, base 45°F
6,480
Growing degree days, base 50°F
5,029
Growing degree days, base 55°F
3,796
Growing degree days, base 60°F
2,761

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January620016
February476041
March3592145
April20623277
May69147543
June8350792
July05401,004
August0504969
September9283724
October12156402
November4211102
December660014

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 14.4 km from Rosamond. 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 USW00003159 (Lancaster Wm J Fox Fld). Public domain.