King tides and a nor'easter flood St. Augustine streets, with a warning in effect until Friday

What happened

The trouble started over the weekend. On Friday, Oct. 23, St. Johns County Emergency Management warned that strong northeast winds and "the highest astronomical tides of the year" could bring moderate to locally major tidal flooding Saturday through Monday. The warning covered the Atlantic coast, the Intracoastal Waterway and the St. Johns River basin. The county cited a National Weather Service briefing that forecast gusts of 35 to 45 mph Sunday into Monday. It told residents to stay off flooded roads, secure loose items such as Halloween decorations and trash cans, and put off boat trips. In Jacksonville, city emergency officials said the Weather Service had advised that the flooding and wind could be similar to a tropical storm, even though this was not a named storm.

The flooding showed up on schedule. News4JAX reported that on Monday morning, Oct. 26, king tides, rain and wind pushed water about two feet above what was expected, swamping streets near Flagler College and City Hall. City Hall opened at noon instead of the usual time. First Coast News reported that Cordova Street near City Hall was under water that morning. A Flagler College student told News4JAX that classes before noon were canceled. Action News Jax showed a neighbor kayaking down Coquina Avenue on Sunday and reported that water came back to that street around 9 a.m. Monday. It also reported that the city delayed trash pickup on flooded streets. First Coast News said the water had gone down by Monday evening.

The Weather Service has extended the warning several times. The version issued at 2:48 a.m. Wednesday, Oct. 28, keeps a coastal flood warning in effect until 2 a.m. Friday, Oct. 30, for the Northeast and Southeast Coastal St. Johns zones, plus coastal Nassau, Duval and Flagler. It calls for "moderate flooding during times of high tide" and says "numerous roads may be closed." It also warns that low-lying homes, businesses and some critical infrastructure will be flooded, and that some shoreline erosion will occur. A High Surf Advisory for breaking waves of 7 to 9 feet runs to the same hour, and the high rip current risk lasts through Friday evening.

Why St. Augustine floods this way

Jessica Beach, the City of St. Augustine's chief resilience officer, told News4JAX this was a nor'easter arriving "in the peak of our King Tide season." She told First Coast News it was compound flooding, with rain, king tides and a strong nor'easter all hitting at once.

Her explanation matters for anyone house-hunting. Beach said much of the city's storm drain system works by gravity. That works under normal tides, but during extreme tides "that water is finding any weak point." She said a recently finished drainage project in one of the flooded neighborhoods is working as designed. "The bad news is that when the Matanzas River overtops ground elevations, this is where the flooding is actually coming from," she said. In other words, in these events the river comes up over the land. Better drains alone can't stop that.

The bigger fixes are hard. Beach said the city has looked at large-scale options, including the Army Corps of Engineers Back Bay Study, and that keeping the water out would take flood walls and pump stations, "basically looking to hold back the entire Matanzas River." She also said similar conditions hit the area around this time in 2025.

Some work is already underway. On Oct. 9, News4JAX reported that the Florida Department of Transportation is replacing the aging bayfront seawall from the Bridge of Lions toward Charlotte Street. The project costs nearly $20 million, and one goal is better protection for A1A from king tides. Work began in June, and the project isn't expected to finish until fall 2027. That same Oct. 9 story reported king tides combined with the outer edges of Hurricane Isaias earlier this month, so this is the second round of high-tide flooding concerns in October.

The numbers that matter

• Wind and tide forecast (Oct. 23 county notice): gusts of 35 to 45 mph Sunday into Monday, with moderate to locally major tidal flooding possible Saturday through Monday.
• St. Augustine on Monday: water about two feet above what was expected, according to News4JAX.
• Observed water at Mayport: We couldn't pull observed water levels for NOAA's St. Augustine Beach station; it offers tide predictions only. So we checked NOAA's Mayport (Bar Pilots Dock) gauge at the mouth of the St. Johns River, the nearest station with observed data we could get. Preliminary data show daily peaks above mean higher high water (the average height of each day's higher high tide) of about 1.9 feet on Oct. 24, 2.2 feet on Oct. 25, 2.4 feet on Oct. 26 and 2.4 feet on Oct. 27. The highest reading was about 2.40 feet near 10:30 a.m. Tuesday.
• The rest of this week: NOAA predicts these midday high tides at St. Augustine Beach, in feet above mean lower low water: 6.49 at 10:10 a.m. Wednesday, 6.36 at 11:02 a.m. Thursday, 6.14 at 11:57 a.m. Friday and 5.87 at 12:56 p.m. Saturday. The overnight highs are lower: 5.04 Wednesday night and 4.88 Thursday night. These are astronomical predictions only. NOAA doesn't build in wind, and a northeast wind is what pushes water higher than the table says. One practical point is that the late-morning tides are the ones to plan around this week.
• Surf: breaking waves of 7 to 9 feet under the current advisory. Rip current risk through Friday evening.

What it means if you're moving here

Downtown and historic St. Augustine. This is where the flooding was worst this week, near City Hall, Cordova Street and Flagler College. Charm and walkability come with a real tidal-flood tradeoff in the lowest blocks. Before you make an offer, ask the seller and the city about past high-tide flooding on that specific street. Get an elevation certificate if one exists, and ask whether the house has ever taken water. The city's resilience officer has said the problem is river water topping ground elevations. A house that sits a few feet higher on the same street can have a very different experience.

St. Augustine Beach, Vilano and the north beaches and Ponte Vedra Beach. These sit in the Northeast and Southeast Coastal St. Johns zones under this week's warning, which also calls for erosion and high surf. Oceanfront and marsh-front homes face both tidal flooding and shoreline loss. Along South Ponte Vedra and Vilano, the county and the Army Corps run a 50-year beach project with periodic renourishment. The county says the first renourishment, in 2020-21, was "severely impacted by a Nor'easter," and the project was repaired again in 2023-24. If you're looking there, ask how the dune in front of the property held up this week.

Inland and western communities such as Nocatee, World Golf Village and Northwest St. Johns. These weren't the focus of this week's reports. Still, the county's Oct. 23 notice named the St. Johns River basin and tidal waterways as areas of concern, not just the beaches. Homes near the river or tidal creeks deserve the same questions.

Insurance timing. FEMA says a new National Flood Insurance Program policy typically has a 30-day waiting period before it takes effect. Exceptions include coverage bought as part of a loan closing, so line up flood coverage before you need it. Our guides to hurricane and flood risk and homeowners and flood insurance cover the basics, and beach or inland walks through the tradeoff.

Day to day. Saltwater on the road isn't harmless rain. Action News Jax and the city both warned that driving through it can damage a car. The county recommends signing up for Alert St. Johns, its emergency notification system.

Our take

This is our opinion, based on the reporting above. The most useful thing for a newcomer to know is that this wasn't a hurricane. It was a nor'easter on top of seasonal king tides, and the city's own resilience officer described it as a recurring pattern: similar conditions about this time last year, plus a king-tide scare tied to Hurricane Isaias earlier this month. In the lowest parts of St. Augustine, fall high-tide flooding is something to plan around, not a once-in-a-decade surprise.

The tradeoff is real. The places that flood are often the places people move here for, like the walkable historic core, the bayfront and the barrier island. We don't think that rules them out. It means price, elevation, insurance and your tolerance for an occasional late start or detour belong in the same conversation. Higher ground, even on the same street, can make a big difference.

Here's what we're watching:

• Whether water rises again around this week's late-morning high tides before the warning ends at 2 a.m. Friday.
• How the bayfront seawall replacement holds to its fall 2027 finish.
• What the city does next on the larger Back Bay options, which it has described as very difficult.
• How the north beaches' dunes and renourished sand held up to this week's surf.

We'll update this note if the county or city publishes damage or erosion reports.