ZIP 77640 Zone 9b

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

Nearest qualified station: PORT ARTHUR SE TX AP, TX US (USW00012917), 6.8 miles from the Census ZCTA internal point for this ZIP.

Median last 32°F is February 14. Median first 32°F is December 7. The 50% growing-season length is 301 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%January 17Earlier date. A last 32°F on or after this day is common.
50%February 14Median.
10%March 13Later 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 15Earlier date. A first 32°F on or before this day is uncommon.
50%December 7Median.
90%January 9Later 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%338
50%301
90%263

28°F threshold

10%50%90%
Last, on or afterMarch 3January 28December 23
First, on or beforeDecember 1January 1February 3
Season at least365 days338 days300 days

36°F threshold

10%50%90%
Last, on or afterMarch 27March 4February 5
First, on or beforeNovember 3November 23December 12
Season at least298 days264 days235 days

Station PORT ARTHUR SE TX AP, TX US (USW00012917). Completeness flag S, 28 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 98.7%. Freeze dates are conditional on that threshold occurring. Elevation 4.9 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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