First Coast
Mayport Water Temperature
The St. Johns River mouth, the jetties, and Hanna Park.
Sea-surface temperature
Cool but comfortableWarming · last two weeks
That is about 3°F warmer than average for this time of year, and warming over the last two weeks. The November average here is 71°F.
Updated Saturday, November 7 — sea-surface temperature modeled for Mayport by Open-Meteo.
Out in the open Gulf, NOAA buoy 41112 — 23 miles offshore — is reading 74°F. Deep water offshore runs cooler than the shallows in summer and warmer in winter, so it won't match the beach.
For swimming
Cool but comfortable
Refreshing rather than cold — comfortable once you're past the first minute.
For fishing
Everything waking up
The transition range, and arguably the widest-open the fishery gets. Snook slide out of the rivers and creeks, redfish spread back across the flats, and bait starts showing on the beaches.
The last two weeks
| Date | Average |
|---|---|
| Oct 25 | 71.6°F |
| Oct 26 | 71.1°F |
| Oct 27 | 70.7°F |
| Oct 28 | 71.2°F |
| Oct 29 | 71.2°F |
| Oct 30 | 71.2°F |
| Oct 31 | 71.6°F |
| Nov 1 | 71.6°F |
| Nov 2 | 71.8°F |
| Nov 3 | 72°F |
| Nov 4 | 73°F |
| Nov 5 | 73.8°F |
| Nov 6 | 74.3°F |
| Nov 7 | 73.8°F |
Mayport water temperature by month
Averaged from 3 years of daily sea-surface temperature (2023–2025). The range column is the coolest and warmest daily average recorded in that month over the period — a guide to how much any given year can differ, not a record high and low.
| Month | Range | Average |
|---|---|---|
JanJanuary Bracing | 52–63°F | 60°F |
FebFebruary Bracing | 56–67°F | 60°F |
MarMarch Bracing | 58–69°F | 64°F |
AprApril Cool but comfortable | 66–76°F | 71°F |
MayMay Warm | 73–81°F | 77°F |
JunJune Warm | 76–85°F | 81°F |
JulJuly Very warm | 80–87°F | 84°F |
AugAugust Very warm | 80–88°F | 85°F |
SepSeptember Very warm | 80–85°F | 83°F |
OctOctober Warm | 71–83°F | 76°F |
NovNovembernow Cool but comfortable | 65–76°F | 71°F |
DecDecember Bracing | 59–68°F | 63°F |
Warmest
85°FAugust
Coolest
60°FJanuary
Warmest on average in August at 85°F; coolest in January at 60°F.
The water at Mayport
Mayport guards the mouth of the St. Johns River, where a huge volume of water funnels between two long rock jetties. That current makes it one of the most productive spots on the First Coast: bull redfish stack up in the fall, sheepshead and black drum work the rocks year-round, and flounder ambush the sand edges. Just south, the beach at Hanna Park — 'the Poles' — is the local surf and surf-fishing beach.
the St. Johns River mouth & the jetties
What moves the water temperature here
The Gulf shelf off this coast is shallow, which is why the water swings so much more between summer and winter than open ocean at the same latitude does. Shallow water heats fast and gives that heat up fast: a single strong winter cold front can pull the inshore bays several degrees down in a couple of days, while the beaches a mile offshore barely move. Wind direction matters too — a sustained offshore breeze can pull cooler water up from below and drop the beach temperature noticeably in a morning.
Inshore bays, canals and flats run warmer than the beach through the summer and colder through the winter, for the same reason. The reading above is for the open water at Mayport; expect the back bays to be a few degrees either side of it depending on the season.
Common questions
- What is the water temperature at Mayport right now?
- The water at Mayport is currently about 74°F (23°C). The November average here is 71°F.
- Is the water warm enough to swim at Mayport in November?
- November averages 71°F at Mayport, which most people would call cool but comfortable. Refreshing rather than cold — comfortable once you're past the first minute.
- When is the water warmest at Mayport?
- August is the warmest month on average at 85°F, and January the coolest at 60°F. 6 months of the year average 75°F or above.
- Why does the water temperature change so quickly here?
- The Gulf shelf off this coast is shallow, so it heats and cools far faster than deep open ocean. A strong winter cold front can pull the inshore water down several degrees in a couple of days, and a sustained offshore wind can drop beach temperatures in a single morning by pulling cooler water up from below.