| Lanikai Beach | Hawaii | Coastal Waters | 26.8°C(80.2°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Laniloa Beach | Hawaii | Coastal Waters | 26.7°C(80.1°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Larsen's Beach | Hawaii | North Pacific Ocean | 27°C(80.6°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Las Tunas Beach | California | Gulf of California | 20.2°C(68.4°F) | July, August, September, October | Live SST → |
| Laudholm Beach | Maine | James Bay | 16.5°C(61.7°F) | June, July, August, September | Live SST → |
| Laurence Harbor Beach | New Jersey | James Bay | 21.9°C(71.4°F) | June, July, August, September | Live SST → |
| Lāwaʻi Beach | Hawaii | North Pacific Ocean | 27.1°C(80.8°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Leadbetter Beach | California | Gulf of California | 18.6°C(65.5°F) | July, August, September, October | Live SST → |
| Lee Street Beach | Illinois | James Bay | 20.1°C(68.2°F) | July, August, September, October | Live SST → |
| Leucadia State Beach | California | Gulf of California | 21.3°C(70.3°F) | July, August, September, October | Live SST → |
| Lewes Public Beach | Delaware | Coastal Waters | 23.1°C(73.6°F) | July, August, September | Live SST → |
| Lido Beach | New York | James Bay | 21.7°C(71.1°F) | June, July, August, September | Live SST → |
| Lighthouse Beach | New York | James Bay | 21.4°C(70.5°F) | June, July, August, September | Live SST → |
| Lighthouse Beach | Maine | James Bay | 14.1°C(57.4°F) | July, August, September, October | Live SST → |
| Lighthouse Field State Beach | California | Gulf of California | 14.9°C(58.8°F) | August, September, October, November | Live SST → |
| Limantour Beach | California | Coastal Waters | 13.2°C(55.8°F) | August, September, October, November | Live SST → |
| Limewood Beach | Connecticut | James Bay | 22.1°C(71.8°F) | July, August, September | Live SST → |
| Lingan Street Beach | Massachusetts | James Bay | 17.8°C(64°F) | June, July, August, September | Live SST → |
| Lions Beach | Michigan | James Bay | 20.5°C(68.9°F) | July, August, September, October | Live SST → |
| Little Beach | Hawaii | Coastal Waters | 26.8°C(80.2°F) | January, February, March, April, May, June, July, August, September, October, November, December | Live SST → |
| Little Beach | New Jersey | Coastal Waters | 22.3°C(72.1°F) | July, August, September | Live SST → |
| Little Beach | Massachusetts | James Bay | 17.6°C(63.7°F) | June, July, August, September | Live SST → |
| Little Beach | Maine | James Bay | 16.9°C(62.4°F) | June, July, August, September | Live SST → |
| Little Beach | Maine | James Bay | 16.1°C(61°F) | June, July, August, September | Live SST → |
| Little Beach | United States | Coastal Waters | 22.6°C(72.7°F) | July, August, September | Live SST → |
| Little Beach | United States | James Bay | 13.5°C(56.3°F) | July, August, September, October | Live SST → |
| Little Corona Del Mar Beach | California | Gulf of California | 20.8°C(69.4°F) | July, August, September, October | Live SST → |
| Little North Beach | Washington | Coastal Waters | 11.4°C(52.5°F) | June, July, August, September | Live SST → |
| Little Pond Beach | Maine | James Bay | 12.3°C(54.1°F) | July, August, September, October | Live SST → |
| Little River State Beach | California | Coastal Waters | 12.8°C(55°F) | July, August, September, November | Live SST → |
| Littleneck Beach | Washington | Coastal Waters | 11.4°C(52.5°F) | June, July, August, September | Live SST → |
| Lloyd Beach | New York | James Bay | 21.5°C(70.7°F) | June, July, August, September | Live SST → |
| Lone Ranch Beach | Oregon | Coastal Waters | 11.8°C(53.2°F) | August, September, October, November | Live SST → |
| Long Beach | New York | James Bay | 21.7°C(71.1°F) | June, July, August, September | Live SST → |
| Long Beach | New York | James Bay | 21.4°C(70.5°F) | June, July, August, September | Live SST → |
| Long Beach | New York | James Bay | 20.9°C(69.6°F) | July, August, September, October | Live SST → |
| Long Beach | Connecticut | James Bay | 22.3°C(72.1°F) | July, August, September | Live SST → |
| Long Beach | Connecticut | James Bay | 22.3°C(72.1°F) | July, August, September | Live SST → |
| Long Beach | North Carolina | Gulf of Mexico | 27°C(80.6°F) | June, July, August, September | Live SST → |
| Long Spit | Washington | Coastal Waters | 11.4°C(52.5°F) | June, July, August, September | Live SST → |
| Longnook Beach | Massachusetts | James Bay | 18°C(64.4°F) | June, July, August, September | Live SST → |
| Lordship Beach | Connecticut | James Bay | 22.3°C(72.1°F) | July, August, September | Live SST → |
| Lorenzo Beach | California | Gulf of California | 20.5°C(68.9°F) | July, August, September, October | Live SST → |
| Lower Beach | New York | James Bay | 20.9°C(69.6°F) | July, August, September, October | Live SST → |
| Lucia Beach | Maine | James Bay | 14.1°C(57.4°F) | July, August, September, October | Live SST → |
| Lumahaʻi Beach | Hawaii | North Pacific Ocean | 27.1°C(80.8°F) | January, February, April, May, June, July, August, September, October, November, December | Live SST → |
| Lynch Park Beach | Massachusetts | James Bay | 17.5°C(63.5°F) | June, July, August, September | Live SST → |
| Lynn Beach | Massachusetts | James Bay | 17.6°C(63.7°F) | June, July, August, September | Live SST → |
| M Street Beach | Massachusetts | James Bay | 17.6°C(63.7°F) | June, July, August, September | Live SST → |
| Mackerel Cove Beach | Rhode Island | James Bay | 19.6°C(67.3°F) | July, August, September, October | Live SST → |