Marco Island water temperature by month Swimmable from February through December.
Where these numbers come from Every number on this page is a satellite reading of the open water off Marco Island, not a sensor in the surf. The Naples pier lost its water-temperature sensor in the rebuild after Hurricane Ian, and the nearest one still reporting is a buoy about 80 miles out in the Gulf.
Set beside a buoy out in open water, this record usually lands within about a degree of it; beside a pier sensor in the shallows, a degree or two out. That gap is the surf zone — shallow water moves faster than the open ocean, warmer over sun-warmed sand on a calm afternoon and cooler after a blow. Read this as the water off the beach rather than the water at your ankles.
Month by month Month Typical Feels January 67° refreshing February 71° refreshing March 74° perfect April 78° perfect May 83° bath-warm June 86° bath-warm July 88° bath-warm August 88° bath-warm September 87° bath-warm October 82° bath-warm November 77° perfect December 71° refreshing
The year at a glance swimmable 60° 70° 80° 90° 100° 88° 67° J F M A M J J A S O N D January: typically 67° — refreshing February: typically 71° — refreshing March: typically 74° — perfect April: typically 78° — perfect May: typically 83° — bath-warm June: typically 86° — bath-warm July: typically 88° — bath-warm August: typically 88° — bath-warm September: typically 87° — bath-warm October: typically 82° — bath-warm November: typically 77° — perfect December: typically 71° — refreshing
Typical for this month Typically about 82° in October — bath-warm.
from the satellite record for the water off Marco Island
bath-warm
bath-warm 80° and up perfect 72–79° refreshing 65–71° brisk below 65° 82° typical for October
About this reading The satellite record for the water off Marco Island covers about fifteen miles of open water off this beach. Nothing is in the water here — a satellite reads the surface of that whole stretch of ocean once a day, and the surf zone itself is too narrow to appear in it.
Warm water says nothing about surf, rip currents, or bacteria — check local lifeguard flags and advisories.