Livermore climate

Livermore Frost Dates and Growing Season

NOAA 1991-2020 normals for Livermore, 4.3 km from Livermore, elevation 393 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Livermore. 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 February 15 and the first fall freeze around December 2, a growing season of about 292 days.

Median at 36°F
last March 25, first November 18
Median at 32°F
last February 15, first December 2
Median at 28°F
last January 10, first December 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°FApr 13Apr 8Apr 3Mar 31Mar 25Mar 18Mar 13Mar 7Feb 26
32°FMar 13Mar 5Feb 28Feb 22Feb 15Feb 9Feb 1Jan 26Jan 12
28°FFeb 10Jan 31Jan 24Jan 15Jan 10Jan 3Dec 30Dec 26Dec 19
24°FJan 20Jan 13Jan 9Jan 4Jan 1Dec 30Dec 27Dec 21Dec 13
20°F–––––––––
16°F–––––––––

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°FNov 4Nov 9Nov 12Nov 14Nov 18Nov 21Nov 24Nov 28Dec 2
32°FNov 16Nov 22Nov 25Nov 29Dec 2Dec 5Dec 9Dec 14Dec 28
28°FNov 29Dec 4Dec 8Dec 13Dec 18Dec 24Dec 30Jan 6Jan 17
24°FDec 7Dec 14Dec 21Dec 26Dec 30Jan 1Jan 4Jan 9Jan 14
20°F–––––––––
16°F–––––––––

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°F268257250245238232226219210
32°F330317306299292284276268257
28°F365365356349343337332322310
24°F365365365365365365365360350
20°F365365365365365365365365365
16°F365365365365365365365365365

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
99% of years
28°F or colder
76% of years
24°F or colder
24% of years
20°F or colder
0% of years
16°F or colder
0% 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
2,569
Cooling degree days, base 65°F
903
Growing degree days, base 40°F
7,468
Growing degree days, base 45°F
5,700
Growing degree days, base 50°F
4,091
Growing degree days, base 55°F
2,747
Growing degree days, base 60°F
1,692

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January530033
February392070
March3251157
April21510247
May10653412
June25140566
July2244707
August2237701
September11170609
October9648417
November3351138
December532035

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 4.3 km from Livermore. 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 USC00044997 (Livermore). Public domain.