Because cars can’t swim.

FloodRoute forecasts which streets in US coastal towns flood at high tide and during king tides: when, how badly and for how long. It's a free iPhone app and a free website with live street-level flood maps for 39 coastal towns and neighborhoods in 6 states. FloodRoute is made in Marin County, California, by Axiomic, LLC.

It combines NOAA tide predictions for the nearest tide station with the measured elevation along every street in each town. When the water is forecast to rise above a road's lowest point, the road is marked as possible (amber), likely (orange) or severe (red) flooding, depending on how far the water rises above it. Where a nearby NOAA gauge measures live water levels, the forecast is corrected when the water is running above or below the tide tables. After each high tide, streets stay marked a little longer, because water drains off roads more slowly than the tide falls. Heavy recent rain raises the next 24 hours.

They're estimates, not guarantees. Wind, storm surge, blocked drains, construction and local quirks can change what actually floods, and new towns launch in Beta until community reports confirm them. In backtests at six NOAA stations (October 2024 to October 2026), the live gauge correction cut the typical error in high-tide water levels over the next 24 hours from about 0.57 ft to about 0.23 ft. Treat FloodRoute as a heads-up: never drive or walk through flood water, and follow local authorities and official warnings.

No. FloodRoute covers coastal tidal flooding only: streets that flood when high tides and king tides push bay or ocean water onto the road. It does not forecast river, creek or flash flooding, drainage failures, or storm surge beyond what nearby gauges currently measure. For those, follow the National Weather Service and local authorities.

The website is free, and so is the core of the iPhone app: the live flood map and tide scrubber, the 7-day flood outlook, community reports, sharing, calendar feeds, one saved place, and a heads-up before flood windows in your home town (plus a king tide heads-up the evening before). FloodRoute Pro adds street-level alerts for up to three saved places, commute alerts, the 30-day planner, the what-if simulator and alerts for more towns. Pro is a monthly or yearly subscription through the App Store. Everyone starts with Pro free, with no payment details, until two days after the next notable high tide in their town (at least 7 and at most 30 days). After that the app switches to the free features; you're never locked out.

39 coastal towns and neighborhoods in 6 states. California: Marin County and San Francisco; Massachusetts: Boston; New York: New York City; Florida: Miami, Tampa, Fort Lauderdale (beta) and North Miami (beta); South Carolina: Charleston (beta); Virginia: Norfolk (beta) and Virginia Beach (beta). Towns marked Beta are new and still being confirmed by community reports. See the full list of covered towns.

Yes. Request your town and share your link with neighbors. The most-requested towns get mapped first, and if you leave your email, we'll tell you the day your town launches.

There are no accounts. Location access is optional and only used while the app is open. Your location is processed on your device and never leaves it unless you submit a flood report (its pin is public) or choose to attach it to a town request. Saved places and commutes stay on your device and sync through your own iCloud. We don't sell your data or use advertising identifiers. See the Privacy Policy.

Yes. Every town and every flood day has its own link, and its preview card shows the forecast in iMessage, Facebook or Nextdoor. Neighbors can open the live map in any browser, with no app needed. You can also subscribe to a town's flood-day calendar or print a flyer for a bulletin board.