High Tide Flooding Outlook for December 2025

The high tide action this month will largely be at the periphery of the country, with nearly every harbor on the West Coast and all of them in Hawaii seeing the likelihood of flooding on or about December 4, during the full moon, and on the December 19 new moon. On the East Coast, Boston is likely to see its highest tides of the year and may exceed the high tide flooding threshold due to tides alone, even without factoring in any weather conditions that could increase flood levels even further. The only other East Coast harbor likely to see flooding is Bar Harbor, Maine, although flooding is possible in many other major harbors along the eastern seaboard, including Charleston, South Carolina, and Port Canaveral, Florida.

Higher than normal high tides — and, of course, lower than normal low tides — will occur around the perigean spring tide, when the Moon is full and closest to Earth. Tides will increase leading up to and after the Winter Solstice, on December 21, due to the increased angle of the Sun relative to the Earth’s equator. In addition, real-time weather conditions, including wind direction and storm surge, may also increase the potential for flooding. In all locations, higher than normal high tides (and lower low tides) should be expected on or around the full moon, on December 4, and the new moon, on December 19.

Note that while NOAA only makes these flooding predictions for harbors with National Ocean Service water level stations, other locations along the coast may experience similar high-water events during these time periods.