Swimming in the United States (USA) in september 2025 Sea temperature by city in september

In september in the United States (USA) swimming conditions vary by city. Details below:

In september in Honolulu (Oahu), New Orleans, Miami, Hawaii, Kauai (Garden Isle), Key West, Maui, Florida, Hilo, Captain Cook, Hana, Houston, Kahului, Kekaha, Kilauea, La'ie, Molokai, Myrtle Beach, Niihau, Pahala, St. Augustine, Tampa, Waianae, Anna Maria Island, Apalachicola, Biscayne National Park, Boynton Beach, Caladesi Island, Cameron, Captiva Island, Carolina Beach, Cedar Key, Clearwater, Cocoa Beach, Dauphin Island (Alabama), Edisto Beach, Egmont Key, Fort Lauderdale, Fort Pierce, Fort Walton Beach, Grand Isle, Gulf Islands National Seashore, Gulf Shores (Alabama), Hernando Beach, Holly Beach, Houma, island of Hawaii (Big Island), Jacksonville, Kahoolawe, Key Largo, Lake Charles, Lanai, Lido Key and Lihue, swimming conditions are perfect! With water reaching a maximum of 83°F and an average of 81°F, going in the water (and staying there!) feels great.

As for Washington D. C., New York City, Philadelphia, Atlantic City, Baltimore and Brooklyn, swimming is pleasant in september. The sea water is 75°F on average (min: 72°F/max: 77°F) so you can easily spend time in the water.

Swimming in september in California, Los Angeles , Boston, San Diego, Cape Cod National Seashore, Encinitas, Hollywood, Malibu and Manhattan Beach is possible but the sea is generally cool. So though the sea temperature may sometimes reach 70°F, it can also go as low as 64°F. Note that the average is 67°F.

Swimming in september in Channel Islands National Park, Gaviota and Hampton Beach is possible... with a wetsuit! Indeed, the water is cold at this time of year with an average temperature of 62°F (min: 58°F/max: 65°F).

Forget about swimming in Anchorage, San Francisco, Seattle, Anchor Point, Dillingham, Dutch Harbor, Ketchikan, Long Beach (Washington), Portland, Bar Harbor (Maine), Big Sur, Cambria, Carmel-by-the-Sea, Cordova, Crescent City, Eureka, Gambell (St. Lawrence Island), Golden Gate National Recreation Area, Gualala, Haines, Half Moon Bay, Jenner, Kenai, Klamath, Kodiak, Kotzebue, La Push (Washington) and Lincoln City (Oregon) in september! The water temperature is freezing, reaching as low as 50°F (and only 54°F at the best of times). Our advice: plan on sightseeing, and don't bring your beach towel!