CoastWarn
NOAA coastal flood alerts
About
Receive timely alerts for coastal flooding based on your custom water-level thresholds. Monitor NOAA data, get tide charts, and stay informed about potential flood events affecting your property or boat.
What's New in CoastWarn
1.1.0
September 28, 2026
Flood alerts - Alert details now show when NWS says the hazard ends, and say "Ended" once it has. - When NWS gives no end time, the app shows when NWS will next update the alert. - Alert details now include the NWS instructions (precautionary and preparedness actions) whenever NWS sends them. - NWS text keeps its tide tables and road lists laid out as NWS wrote them. Tides - High and low tide rows show the forecast peak, so they match your flood alert. When the forecast peak differs from the NOAA tide table by 15 minutes or more, the row shows the tide table time too. - A tide that has already peaked no longer shows as the next high. - Chart time labels no longer overlap. Fewer false alarms about monitoring - Water level gauges often report 12 to 18 minutes late. CoastWarn now waits until a reading is 45 minutes old before it warns you about a missed update or shows the reading's age. Notices during an active flood alert are never delayed.
MoreSubscriptions & In-App Purchases
$19.99
CoastWarn Lifetime Unlock
Unlock CoastWarn with a one-time purchase
FAQ
What is CoastWarn?
CoastWarn is an application that monitors official NOAA water-level data and sends you alerts when observed levels reach a threshold you set. It helps users stay informed about potential coastal flooding.
How does CoastWarn work?
You can find supported NOAA stations by ZIP code or map, then set a water-level threshold. CoastWarn will then send you flood alerts and 'all-clear' notifications with current readings and trends.
What data does CoastWarn use?
CoastWarn utilizes official NOAA CO-OPS water-level observations and tide predictions. It also provides regional model projections where available.
Is CoastWarn free to use?
CoastWarn offers a 7-day free trial. After the trial, you can continue using its features with a one-time purchase of $19.99 for CoastWarn Pro Lifetime, which requires no subscription.
What devices does CoastWarn support?
CoastWarn is currently available for iPhone. It requires iOS notification settings to be enabled for timely alert delivery.
How often is CoastWarn updated?
The latest version, 1.1.0, was released on September 28, 2026, with the initial release on September 22, 2026. Update frequency is typically tied to data availability and feature enhancements.
Does CoastWarn have ads?
No, CoastWarn does not contain advertisements. The app is ad-free, with monetization coming from a one-time purchase for Pro features.
What is the age rating for CoastWarn?
CoastWarn has an age rating of 4+. This indicates it is suitable for a wide range of users, including children, for general weather information.
