Leeward — Hurricane Watchfulness for Island Communities

Built for the Caribbean

Island-Specific Status

Not basin-wide hand-waving. Each of 9 island groups gets its own status based on where the system is, where it is going, and how it relates to that island chain.

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 directly from the National Hurricane Center, then turns those basin-wide signals into island-specific status for the Caribbean.

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

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?

The National Hurricane Center (NHC), part of NOAA. This is the same data source used by emergency managers, the Coast Guard, and professional meteorologists.

How often is data updated?

Weather conditions are checked every 15 minutes. During active storms, storm-specific data is updated every 30 minutes from NHC advisories.

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