Leeward — Hurricane Watchfulness for Island Communities

Built for the Caribbean

Island-Specific Status

Not basin-wide hand-waving. 9 Caribbean chains, with 37 specific islands inside them. Pick your chain for hurricane status, or drill into your specific island for marine and beach conditions.

Beach Reports

Daily ranked beaches scored on cruise crowding, surf, sargassum, and water quality. Find the calm, clean water before you drive. US Virgin Islands at launch; more chains as local data sources are added.

Island Life Mode

A peer to Storm Mode, not a sub-mode. Marine forecasts, beach reports, local weather, and daily life signals — the everyday companion when hurricanes aren't on the radar.

Early Attention Cues

Leeward is built for the 90% of the season when people keep checking anyway. It helps you know when there is nothing to do and when it is time to start paying closer attention.

Calm, Useful Notifications

Storm formation, category changes, warnings, and approach alerts. Choose anything from critical-only to daily peace-of-mind updates.

Why This Status

See the factors behind the current level: forecast track, time to closest approach, watches and warnings, storm intensity, and movement.

Watch Multiple Islands

Set one home island and monitor others. Primary and watched island behavior is built for residents, family networks, and property owners.

Trust By Design

Risk decisions are deterministic. Summaries are plain-language. Official NHC data stays visible. No ads, no accounts, no distraction.

How Leeward Works

Data Sources

Leeward pulls from a dozen authoritative sources — NHC, NWS, NOAA AOML, and local meteorological services across the Caribbean — and turns basin-wide signals into island-specific status, conditions, and forecasts.

NHC Tropical Weather Discussion checked every 15 minutes; 5 storm advisory feeds checked every 30 minutes
Storm detection uses deterministic parsing — position, winds, pressure, movement, and warning status are extracted without AI
NWS Coastal Waters & Offshore Forecasts for zone-specific marine conditions; national met services in the Leeward, Windward, Bahamas, Bermuda, T&T, and Jamaica chains for local land forecasts
NOAA AOML AFAI and SIR satellite data for sargassum density, adjusted for local wind direction and shore exposure
USVI DPNR weekly water quality and WICO Port Authority cruise schedule (USVI Beach Reports)
GHCN-Daily station observations and NWS gridpoint QPF for rainfall

Risk Decisions

Leeward does not ask a model to decide whether your island is at risk.

Disturbances are parsed from NHC outlook text using deterministic NLP and pattern matching
Each island group has calibrated thresholds based on origin, distance, forecast path, timing, and warning status
Storm-state logic handles closest approach, movement, watches, warnings, and escalation
The app is built to answer a narrow question well: can this island relax, should it watch, or should it prepare?

The Role of AI

AI is used only to make the output easier to read.

Google Gemini writes the plain-language narrative summaries and localized explanations
All storm detection, risk levels, distance calculations, and warning matching remain deterministic
AI cannot override safety-critical data — if NHC says a hurricane warning is in effect, that is what you see
The summary layer improves readability; it does not replace the decision logic

Validation & Infrastructure

Historical replay and regression tooling are used to test the system against past storms
Hosted on Google Cloud for reliability
Data refreshed automatically on a schedule
Cached per island group for fast response times
Built on open data from NOAA — no proprietary weather models

About

During the 2025 hurricane season, I spent my nights doing what a lot of us do — refreshing NHC, scrolling through VI Weather Lady's updates, and trying to figure out whether the latest tropical wave was actually something to worry about.

I'd wake up at 3am to check the forecast. I'd see the same anxiety playing out across Facebook groups — "Is this one coming our way?" "Should I start boarding up?" "What does this cone mean for St. Thomas?"

I'm a software engineer by trade, and I realized I could build something that would help. Not to replace NHC or the incredible work of local forecasters like VI Weather Lady — but to make it easier to know when there is nothing to do, and when it is time to pay attention to them more closely.

Leeward exists for three reasons: to give something back to the island communities I'm part of, to reduce stress during the quiet stretches when there is genuinely nothing to worry about, and to help people prepare earlier when something real is on the way.

This is a free app. No ads, no premium tier, no investor pressure. Just a tool for the community, built by someone who understands the anxiety of hurricane season.

— John Appleby

Frequently Asked Questions

Is Leeward free?

Yes. Completely free, no ads, no premium tier. This is a community project.

Where does the data come from?

Hurricane data comes from the National Hurricane Center (NHC). Land and marine forecasts come from the U.S. National Weather Service and your island's national meteorological service — BWS, Antigua Met, Dominica Met, T&T Met, Jamaica Met, Bahamas Met — where one publishes, with Apple WeatherKit filling gaps. Beach Reports add NOAA AOML (sargassum), USVI DPNR (water quality), GHCN-Daily (rainfall), and the WICO port schedule (cruise traffic). All sources are official.

How often is data updated?

Hurricane tracking refreshes every 15 minutes; during an active storm, NHC advisories every 30 minutes. Daily forecasts and marine conditions refresh through the day. Beach Report inputs follow their natural cadence — cruise schedule and sargassum daily, water quality on its weekly issue cycle, rainfall every six hours.

What are Beach Reports?

A daily ranked list of the best beaches for swimming, snorkeling, and a good day on the water — combining sargassum, water quality, rainfall, cruise-ship crowding, and marine conditions. USVI only today (St. Thomas, St. John, Water Island); more islands as we add inventory.

What is Island Life mode?

Most of the year there isn't a hurricane. Island Life is the year-round daily surface — local weather, marine conditions, beach picks, and what's worth knowing today. Storm Mode takes over automatically when a system threatens your island.

Does Leeward use AI?

Yes, but only for the readable summary text. The actual status calculation is deterministic: NHC inputs are parsed, scored, and matched to each island group using fixed logic for distance, forecast approach, warnings, and storm state. Read more in How It Works above.

How do I know this is not just an AI weather bot?

Because the app is built around deterministic parsing, island-specific thresholds, storm-state logic, and historical replay testing. The summary text is generated for readability, but the status itself is driven by NHC data and fixed rules.

Is my data private?

Yes. No account, no login, no personal data collected. Push notifications use an anonymous device identifier only. We don't track your location, browsing, or usage. See our full privacy policy.

What islands are covered?

Nine groups: Leeward Islands, Virgin Islands, Puerto Rico, Northern Lesser Antilles, Windward Islands, Hispaniola, Jamaica & Cayman Islands, Bahamas, and Bermuda.

Should I rely only on Leeward during a hurricane?

No. Always follow official guidance from your local meteorological service, the National Hurricane Center, local emergency management, and trusted local forecasters. Leeward is designed to complement those sources, not replace them.

How do notifications work?

Choose your level: Storm Only (critical alerts), Storm Alerts (warnings and significant changes), Peace of Mind (daily summaries and all updates), or Verbose (everything). You can also customize per event type.

Is there an Android version?

Not yet. Leeward is iOS-only for now. An Android version may come in the future.

Know when your island can relax, when it should watch, and when it should prepare

Current Conditions