You mention often about the water temperature in the Gulf. How is this number determined? Is it surface temp or a specific depth?
Good question ... and note that we've started posting water temps in Lake Pontchartrain as well. Temps are typically taken near the surface, but if properly placed, the sensor should ALWAYS remain below the waterline, regardless of tides. (Seems obvious I know, but I've found NOAA guages that popped above the waterline during low-low-water.)
Temperatures that we use for BOTH waters are collected by automated platforms (automated weather and water stations). For the Gulf, the data come from a NOAA/NOS tide gauge on the eastern end of Grand Isle. So it is important to remember that these water temps are from right along the shoreline of Grand Isle .. shallow, protected water that is likely to be on the warm-side most days.
The Pontchatrain data are from a lake platform owned and operated by LUMCON (LA University Marine Consortium). That platform is in the open water in the northwestern portion of the lake.
NOAA Grand Isle Site Link:
Hope this helps.