| Island Beach | California | Gulf of California | 14.9°C(58.8°F) | August, September, October, November | Live SST → |
| Island Park Beach | Rhode Island | James Bay | 20.2°C(68.4°F) | June, July, August, September | Live SST → |
| Jacobs Public Beach | Connecticut | James Bay | 21.6°C(70.9°F) | July, August, September, October | Live SST → |
| Jenner Beach | California | Coastal Waters | 12.8°C(55°F) | August, September, October, November | Live SST → |
| Jenness Beach | New Hampshire | James Bay | 17.2°C(63°F) | June, July, August, September | Live SST → |
| Jennings Beach | Connecticut | James Bay | 22.3°C(72.1°F) | July, August, September | Live SST → |
| Jesse Beach | Maine | James Bay | 12.8°C(55°F) | July, August, September, October | Live SST → |
| Jetty Beach | California | Gulf of California | 14.9°C(58.8°F) | August, September, October, November | Live SST → |
| Johnsons Landing | California | Gulf of California | 20.5°C(68.9°F) | July, August, September, October | Live SST → |
| Jones Beach | California | Coastal Waters | 12.5°C(54.5°F) | August, September, October, November | Live SST → |
| Jones Beach | New York | James Bay | 21.7°C(71.1°F) | June, July, August, September | Live SST → |
| Jones Island Beach | Illinois | James Bay | 19.5°C(67.1°F) | July, August, September, October | Live SST → |
| Jordan Beach | Maine | James Bay | 12.8°C(55°F) | July, August, September, October | Live SST → |
| Josephs Beach | United States | James Bay | 17.6°C(63.7°F) | June, July, August, September | Live SST → |
| Joyce Beach | Maine | James Bay | 13.5°C(56.3°F) | July, August, September, October | Live SST → |
| Jug Handle Beach | California | Coastal Waters | 13.1°C(55.6°F) | August, September, October, November | Live SST → |
| Juneway Beach | Illinois | James Bay | 20.1°C(68.2°F) | July, August, September, October | Live SST → |
| Juniper Beach | Massachusetts | James Bay | 17.5°C(63.5°F) | June, July, August, September | Live SST → |
| Juniper Trail Beach | Rhode Island | James Bay | 20.2°C(68.4°F) | June, July, August, September | Live SST → |
| Ka'anapali Beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Ka'opala Beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaanapali Beach (Maui) | Hawaii | Auau Channel / Pacific Ocean | 27.9°C(82.2°F) | Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec | Live SST → |
| Kaelehuluhulu Beach | Hawaii | Coastal Waters | 27.1°C(80.8°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kahekili Beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kahili Beach | Hawaii | North Pacific Ocean | 27°C(80.6°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaʻakuʻu Beach | Hawaii | North Pacific Ocean | 27.3°C(81.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaihalulu Beach | Hawaii | Coastal Waters | 26.7°C(80.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kailua Beach | Hawaii | Coastal Waters | 26.8°C(80.2°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaimana beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaipapa‘U Beach | Hawaii | Coastal Waters | 26.7°C(80.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kalalau Beach | Hawaii | North Pacific Ocean | 27.1°C(80.8°F) | January, February, April, May, June, July, August, September, October, November, December | Live SST → |
| Kalaloch Beach 1 | Washington | Coastal Waters | 14°C(57.2°F) | June, July, August, September | Live SST → |
| Kalaloch Beach 2 | Washington | Coastal Waters | 14°C(57.2°F) | June, July, August, September | Live SST → |
| Kalani Beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kalapaki Beach | Hawaii | North Pacific Ocean | 27°C(80.6°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kalihiwai Beach | Hawaii | North Pacific Ocean | 27°C(80.6°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaluhikaa Beach | Hawaii | Coastal Waters | 27°C(80.6°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kamalino Beach | Hawaii | North Pacific Ocean | 27.3°C(81.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kamaole III Beach | Hawaii | Coastal Waters | 26.8°C(80.2°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kamilo | Hawaii | Coastal Waters | 26.8°C(80.2°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kanaha Beach | Hawaii | Coastal Waters | 26.7°C(80.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kapahukapu (Manini Beach) | Hawaii | Coastal Waters | 27.3°C(81.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kapalua Beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kauapea Beach | Hawaii | North Pacific Ocean | 27°C(80.6°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kauhala | Hawaii | Coastal Waters | 26.7°C(80.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kaulahao Beach | Hawaii | Coastal Waters | 26.7°C(80.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kauwaha Beach | Hawaii | North Pacific Ocean | 27.3°C(81.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kawaʻaloa Beach | Hawaii | Coastal Waters | 26.9°C(80.4°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Kayostla Beach | Washington | Coastal Waters | 12.9°C(55.2°F) | June, July, August, September | Live SST → |
| Keamano Beach | Hawaii | North Pacific Ocean | 27.3°C(81.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |