ZIP 94509 Zone 9b

California · USDA zone 9b, average annual extreme minimum 25°F to 30°F.

Nearest qualified station: ANTIOCH PUMPING PLT #3, CA US (USC00040232), 3.3 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is January 12. Median first 32°F is December 19. The 50% growing-season length is 343 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

ProbabilityDateHow to read it
90%December 20Earlier date. A last 32°F on or after this day is common.
50%January 12Median.
10%February 1Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

ProbabilityDateHow to read it
10%November 29Earlier date. A first 32°F on or before this day is uncommon.
50%December 19Median.
90%January 12Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this longDays
10%365
50%343
90%315

28°F threshold

10%50%90%
Last, on or afterJanuary 22January 2December 16
First, on or beforeDecember 9December 29January 16
Season at least365 days365 days347 days

36°F threshold

10%50%90%
Last, on or afterMarch 12February 8January 11
First, on or beforeNovember 18December 4December 28
Season at least331 days299 days263 days

Station ANTIOCH PUMPING PLT #3, CA US (USC00040232). Completeness flag R, 19 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 81.3%. Freeze dates are conditional on that threshold occurring. Elevation 18.3 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

Methodology · California cities