Alaska

Alaska's coastline stretches more than 54,000 km — longer than the rest of the United States combined — running from the Inside Passage in the southeast through Prince William Sound and the Gulf of Alaska to the Aleutian chain and the Bering Sea coast. Tides are semidiurnal: two highs and two lows each day, with the higher high and lower low differing noticeably (diurnal inequality). Mean ranges are large by lower-48 standards. Juneau sits at roughly 4.5 m mean range; Homer, at the head of Kachemak Bay on the Kenai Peninsula, reaches approximately 5.4 m. Ketchikan's Tongass Narrows sees a mean range near 4.6 m. These are not rogue numbers — they reflect the Pacific's deep-water tidal wave funneling into constricted Southeast Alaska channels and the Cook Inlet geometry amplifying energy northward. Water temperatures across the Southeast Alaska coast run 7–12 °C in summer, dropping to near 2 °C in winter. Glacial meltwater from outlets like Mendenhall and LeConte adds cold, turbid freshwater pulses that can affect local salinity gradients and tide-gauge readings. Tidal currents through the narrows — Tongass, Gastineau, Wrangell — routinely reach 1–3 knots on spring tides and demand respect from kayakers, skiffs, and charter boats alike. Summer brings extended daylight: Juneau sees roughly 18.5 hours of daylight at the solstice; Anchorage approaches 19.5 hours. This compresses the day's two tidal cycles into light and shapes when anglers, whale-watching operators, and photographers work the water. NOAA CO-OPS maintains the authoritative gauge network for Alaskan ports. TideTurtle predictions for Alaska are generated from Open-Meteo Marine, a free gridded global ocean model; accuracy is typically ±45 minutes on timing and ±0.2–0.3 m on height against observed tides. For passage planning, commercial fishing operations, or any safety-critical decision, verify against NOAA CO-OPS at tidesandcurrents.noaa.gov.