High Tide Flooding Outlook: September 2026

Mean sea levels are generally higher in the late summer and early fall months, due to warmer temperatures and weather patterns, and this month higher tides can be expected around the new moon on September 10 and the full moon on September 26. Expect the elevated water levels to persist for a day or two after each. The Mid-Atlantic, Southeast, Gulf Coast, and the Big Island of Hawaii are the regions most likely to see flooding this month. For most harbors in these areas, NOAA predicts a Slight Chance (now defined as a 5-20% likelihood of flooding) when using the National Ocean Service’s minor flooding threshold, measured against the Mean Higher High Water datum. Norfolk, Virginia, and the Outer Banks community of Duck, North Carolina, have a Medium Chance (up to a 40% likelihood), as will Trident Pier, Cape Canaveral, Florida; Eagle Point, Galveston Bay, Texas; and Hilo, Hawaii. Harbors on the West Coast, in contrast, are unlikely to see flooding this month.

Different thresholds will show more harbors at risk. We use the NOS minor threshold as our benchmark, as we have in previous reports, because its nationally consistent formula makes it the best basis for comparing flooding risk from one harbor to the next. The report can also be generated using the NWS minor threshold, which local forecasters and emergency managers calibrate to reflect where flooding actually causes problems in a specific community. NWS minor is not available at every station.