Tool
Maine Ocean Water Temperature
Sea temperature right now from NOAA sensors, south to north. The question people are really asking is whether they can swim, so that is answered beside each reading.
Portland is 61 degrees and Cutler is 53, a 8 degree difference along one coastline.
| Station | Water | Swimming | Reading taken |
|---|---|---|---|
| Portland | 60.8 F | Bracing, but fine once you are moving. | Wed 8:00 AM |
| Bar Harbor | 56.7 F | Cold. Short swims, and it takes nerve. | Wed 8:00 AM |
| Cutler | 52.9 F | Very cold. Wetsuit weather. | Wed 8:00 AM |
| Eastport | 53.2 F | Very cold. Wetsuit weather. | Wed 8:00 AM |
A year in the water
The sea lags the sun by about six weeks, so the warmest water of the year arrives long after the longest day and September beats June. The gap between the lines is the other half of the story: Downeast is not colder on the day you looked, it is colder all year.
- Portlandpeaked 64° on August 9
- Bar Harborpeaked 61° on August 12
- Cutlerpeaked 55° on October 7
- Eastportpeaked 56° on October 1
Daily means from the hourly NOAA readings over the past twelve months, in Fahrenheit. The dashed line is the June solstice: the water keeps warming for weeks after the longest day, which is why September swimming beats June swimming on this coast.
How long the swimming season is
The same readings, reduced to the decision. Portland gets a real stretch of water most people will swim in; the same threshold Downeast lasts a fraction as long, or is never reached at all.
Longest unbroken stretch of daily means above each threshold, from the past twelve months of NOAA readings, plotted on the calendar year. These are open-coast sensors: a shallow sandy bay on a hot afternoon runs warmer, and a season measured there would be longer at both ends.
Common questions
How cold is the ocean in Maine?
Cold enough that most people do not stay in long. Even at the end of August, when the water is at its warmest, the open coast runs in the fifties and low sixties Fahrenheit. Southern Maine beaches are the warmest, and the water gets colder the further east you go.
Why is the water colder Downeast?
Tidal mixing. The tide range grows enormously toward the Bay of Fundy, and all that water churning over the bottom keeps a cold, well-mixed column rather than letting a warm surface layer form. Eastport can be eight degrees colder than Portland on the same day.
When is Maine water warmest?
Mid-August to early September. The sea lags the air by roughly six weeks, so the warmest water arrives well after the longest day, and September swimming is usually better than June swimming.
What about the beaches in southern Maine?
Warmer than these readings suggest. Only four NOAA stations on the Maine coast report water temperature and the southernmost is Portland, so the sandy beaches people actually swim at are all south of the nearest sensor. The shallow bays at Ogunquit, Wells and Old Orchard Beach warm up over a hot afternoon in a way that an open-coast sensor at a fixed depth never sees, and a cove on an outgoing tide over hot sand can be several degrees above the water a mile offshore.
