Hail Sentinel

Hail Sentinel: hail detection, alerts, and analysis, built on Anvil, our own machine-learning model.

Most weather apps warn a county at a time. Some go address-level, but still read the same generic weather data. We run Anvil over dual-polarization radar every two minutes. Built to find hail, not weather in general: when hail is closing in, where the storm is on live radar, and a record of what fell once it passed.

WHAT YOU GET FOR FREE
- Real-time push the moment hail is closing in on your address
- Every severe warning, at full precision. Safety alerts are never behind a paywall
- Live storm radar, colored by what's actually falling
- Today's and tomorrow's hail outlook
- One saved location
- Neighborhood hail history, refreshed each season

Free and Premium run on the same hail detection. Premium doesn't make detection better. It gives you more warning, more places, more tools.

PREMIUM
- Earlier heads-up. Watches hours ahead, and a nudge as a storm turns your way. Varies by storm.
- After-the-Storm Reports. A timestamped record of peak hail size, timing and radar evidence, formatted for an insurance conversation
- The full 7-day hail outlook instead of 2 days
- Up to 4 saved locations, each with its own alerts, forecast and history
- Live GPS alerts. They follow you as you drive, not a fixed address
- Playbooks. Automatic actions when hail threatens: an instant push, an optional webhook for your smart home, and a timestamped evidence record
- SMS and email backup of the same alerts
- Neighborhood hail history in real time

WATCH, WIDGETS AND CARPLAY
- Apple Watch app and complications
- Home Screen widgets: today's hail chance, 7-day outlook, nearby storm cells
- Lock Screen widgets (iOS 16+)
- CarPlay with active alerts and Live GPS status

BUILT ON OUR OWN HAIL SCIENCE
We built our own detector. Anvil is a machine-learning model trained on the dual-pol radar signature of hail itself, fusing radar, satellite, verified ground reports and forecast models. It weighs 83 signals per prediction and re-scores every storm nationwide on a 1 km grid every two minutes. Zero clear-day and zero winter false alarms in our test battery. Not a MESH/MRMS passthrough.

No system on Earth catches every stone. Rather than pretend otherwise, we work on being the most accurate you can get and tell you plainly what we can and can't see.

PRIVACY
Your hail reports train places, not people. They improve detection for areas, never to profile you. We don't sell your data.

SUBSCRIPTION
Premium is an auto-renewing subscription at $6.99 per month or $49.99 per year. Founding Member pricing of $3.99 per month or $29.99 per year runs through October 31, 2026 and stays locked in for as long as you're a member.

Payment is charged to your Apple ID at confirmation of purchase. Your subscription renews automatically unless auto-renew is turned off at least 24 hours before the current period ends, and your account is charged for renewal within 24 hours of that. Manage your subscription and turn off auto-renew in your Apple ID Account Settings. Any unused portion of a free trial is forfeited when you buy a subscription.

Terms of Use: https://hailsentinel.com/legal/terms
Privacy Policy: https://hailsentinel.com/legal/privacy

IMPORTANT
Hail Sentinel supplements but does not replace official National Weather Service warnings. Always follow local emergency guidance. Alert delivery is not guaranteed. It depends on radar coverage, data feeds, connectivity and your device settings. A quiet app does not mean a quiet sky, so keep a second way to receive official warnings.

After-the-Storm Reports record hail conditions at your address. They do not assess or certify property damage. That is your adjuster's determination. Hail Sentinel is not an insurance product.

Hail Sentinel is available only in the contiguous United States, and is not affiliated with, endorsed by, or sponsored by the National Weather Service, NOAA, or any government agency.