Galveston Island State Park water temperature by month

Swimmable from April through November.

Month by month

Month Typical Feels
January 56° brisk
February 60° brisk
March 67° refreshing
April 74° perfect
May 81° bath-warm
June 85° bath-warm
July 86° bath-warm
August 88° bath-warm
September 85° bath-warm
October 79° perfect
November 71° refreshing
December 62° brisk

The year at a glance

swimmable 50° 60° 70° 80° 90° 100° 88° 56° JFMAMJJASOND January: typically 56° — brisk February: typically 60° — brisk March: typically 67° — refreshing April: typically 74° — perfect May: typically 81° — bath-warm June: typically 85° — bath-warm July: typically 86° — bath-warm August: typically 88° — bath-warm September: typically 85° — bath-warm October: typically 79° — perfect November: typically 71° — refreshing December: typically 62° — brisk

The water right now

Typically about 79° in October — perfect.

from the San Luis Pass station, about 12 miles away

perfect

bath-warm 80° and up perfect 72–79° refreshing 65–71° brisk below 65° 79° typical for October

Seaweed season

On the Texas Gulf coast, sargassum season runs from April through July, heaviest from April through May.

Texas beaches get sargassum every year, but no month range is published for them specifically. The window here follows NOAA, which puts the Gulf's own sargassum peak in April and May, ahead of the summer arrivals from the Caribbean.

  1. January: rare
  2. February: rare
  3. March: rare
  4. April: peak season
  5. May: peak season
  6. June: some seaweed
  7. July: some seaweed
  8. August: rare
  9. September: rare
  10. October: rare
  11. November: rare
  12. December: rare

This is a pattern, not a forecast. The lab that watches this says plainly that predicting seaweed on an individual beach is difficult or impossible — whether it comes ashore depends on winds, tides and currents nobody can call ahead. The bulletins track how much is out there and look about a month on.

From the Sargassum Watch System, the Optical Oceanography Lab at the USF College of Marine Science. Read the current bulletin for this month's outlook.

Jellyfish season

What usually turns up on the Texas coast, and when.

  • Texas Parks and Wildlife says the Portuguese man-of-war floats in on the currents and washes up on Texas beaches during the spring to late summer. Texas Parks and Wildlife — jellyfish and their kin
  • Their advice is to read the sand before the water: walk the beach first and see whether any are washed up, which tells you they are about — and never step on one, because the stinging cells stay active after the animal dies. Texas Parks and Wildlife — jellyfish and their kin

This is what a season usually looks like, not a forecast of any particular week. Jellyfish drift on wind and current, so the people who watch them say there are tendencies but no guarantees — the lifeguard flags on the day beat any calendar.

About this reading

The San Luis Pass station sits in an inlet; surf-zone water can run a few degrees off this reading.

Reading from the San Luis Pass station, about 12 miles away.

Warm water says nothing about surf, rip currents, or bacteria — check local lifeguard flags and advisories.