Maine (United States): where to swim in September?
Maine, in September: the sea is at 15.5 °C on average along the coast, from 13.8 °C to 17.4 °C depending on the spot. Where the water is warmest (17.4 °C), it is cool. Swimming is fine if you like cool water: you get used to it after a few minutes, especially in mild weather.
Sea temperature, month by month
| Month | Average temperature | Depending on the spot | Where it is warmest |
|---|---|---|---|
| January | 6.7 °C | 6.1 °C – 7.4 °C | very cold |
| February | 5.0 °C | 4.4 °C – 5.9 °C | very cold |
| March | 4.5 °C | 3.9 °C – 5.3 °C | very cold |
| April | 5.5 °C | 5.0 °C – 6.1 °C | very cold |
| May | 8.1 °C | 7.1 °C – 9.2 °C | very cold |
| June | 11.7 °C | 9.9 °C – 14.0 °C | cold |
| July | 16.0 °C | 13.2 °C – 18.9 °C | cool |
| August | 17.1 °C | 14.6 °C – 19.8 °C | pleasant |
| September | 15.5 °C | 13.8 °C – 17.4 °C | cool |
| October | 13.2 °C | 12.5 °C – 14.0 °C | cold |
| November | 10.7 °C | 10.5 °C – 10.9 °C | cold |
| December | 8.7 °C | 8.2 °C – 9.1 °C | very cold |
Compared with August, the water cools down by 1.6 °C in September. The warmest month: August (17.1 °C). The coldest: March (4.5 °C).
Nearby, in September
- Massachusetts 19.0 °C · pleasant
- New York 21.5 °C · pleasant
- New Jersey 22.7 °C · warm
And right now?
For the temperature measured right now, station by station and to the hour: Maine: water temperature
Frequently asked questions
What is the sea temperature in September?
Maine, in September: 15.5 °C on average along the coast, from 13.8 °C in the coolest waters to 17.4 °C in the warmest (average of the years 2011 to 2025).
Can you swim in September?
Where the water is warmest (17.4 °C), it is cool. Swimming is fine if you like cool water: you get used to it after a few minutes, especially in mild weather.
What is the best month for swimming?
The water is warmest in August (17.1 °C on average) and coldest in March (4.5 °C). Even where it is warmest, the water never reaches 20 °C in any month; the three warmest months are: August, July, September.
What temperature do you need to swim comfortably?
Below 15 °C the water is cold: the cold takes your breath away and tires you quickly. Between 20 °C and 25 °C most people find it pleasant. Below 10 °C it is very cold.
Where do these temperatures come from?
These are averages of the sea surface temperature from 2011 to 2025, computed from NOAA satellite images (OISST, one value about every 50 km), in a 100 km strip along the coasts of the main country: distant territories (overseas, remote islands) are not counted. It is an estimate, not a measurement taken at the beach: lakes and rivers are not included.