Martinez climate

Martinez Frost Dates and Growing Season

NOAA 1991-2020 normals for Martinez Wtp, 1.9 km from Martinez, elevation 40 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Martinez Wtp. 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 28 and the first fall freeze around November 22, a growing season of about 266 days.

Median at 36°F
last April 10, first November 7
Median at 32°F
last February 28, first November 22
Median at 28°F
last January 23, first December 9

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 3Apr 28Apr 20Apr 15Apr 10Apr 4Mar 30Mar 23Mar 15
32°FApr 5Mar 22Mar 11Mar 5Feb 28Feb 24Feb 17Feb 9Jan 29
28°FFeb 25Feb 15Feb 5Jan 30Jan 23Jan 18Jan 12Jan 3Dec 25
24°FJan 27Jan 18Jan 13Jan 8Jan 4Dec 31Dec 29Dec 22Dec 11
20°FJan 19Jan 13Jan 9Jan 5Jan 3Jan 1Dec 31Dec 30Dec 21
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°FOct 27Oct 31Nov 2Nov 4Nov 7Nov 10Nov 13Nov 16Nov 21
32°FNov 7Nov 12Nov 15Nov 19Nov 22Nov 25Nov 29Dec 3Dec 10
28°FNov 20Nov 27Dec 1Dec 5Dec 9Dec 13Dec 20Dec 29Jan 6
24°FDec 3Dec 9Dec 14Dec 19Dec 26Dec 30Jan 4Jan 10Jan 19
20°FDec 20Dec 28Dec 30Dec 31Jan 2Jan 4Jan 9Jan 11Jan 19
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°F239230222216210204198191182
32°F302289280272266258251240226
28°F355344337330323316309298286
24°F365365365365365360352344334
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
100% of years
28°F or colder
93% of years
24°F or colder
50% of years
20°F or colder
11% 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
3,026
Cooling degree days, base 65°F
544
Growing degree days, base 40°F
6,660
Growing degree days, base 45°F
4,932
Growing degree days, base 50°F
3,421
Growing degree days, base 55°F
2,182
Growing degree days, base 60°F
1,227

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January603011
February444040
March3710117
April2515208
May12935371
June33105522
July7156614
August10132588
September3390507
October15121335
November395094
December600015

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 1.9 km from Martinez. 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 USC00045378 (Martinez Wtp). Public domain.