Although ocean conditions vary from year to year, water temperatures are less variable than air temperatures, so these averages can provide useful information for planning beach activities such as swimming or fishing.

The water temperature tables in the NODC Coastal Water Temperature Guide (CWTG) are:

• near real-time temperatures from: NOAA's National Ocean Service (NOS) tidal stations and Physical Oceanographic Real-Time System (PORTS®) and
• most recent (within the past six hours) temperatures from NOAA's National Data Buoy Center (NDBC) moored buoys, and
• average water temperatures computed from long-period records ranging from several years to several decades depending on how long observations have been taken at a given station.

Water temperatures vary more along the Atlantic and Pacific coasts of the United States, so for these stations two-week averages are presented from April through October. For the Gulf coast, only monthly averages are presented.

Water temperature maps, which support interactive browsing of the real-time temperatures, are also available on the Google Map-based Web pages.