GRAT: Mountain Storm Weather

Ski tour & summit storm risk

Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.

GRAT is a decision-support tool for mountaineers, ski tourers and hikers. It combines official weather warnings, high-resolution weather models and station measurements into one risk level for your position and altitude: Safe, Watch, Danger. WINTER MODE Turns on by itself when there is snow cover, snowfall, or a freezing level below you. • The lowest level reads "Low weather risk" instead of "Safe". • Fresh snow (past and next 24 hours), snow depth, time to sunset • How fast exposed skin can freeze (Environment Canada wind chill table) • GRAT does not assess avalanche danger. One tap opens your region's official avalanche bulletin. WHAT GRAT SHOWS • Shower and thunderstorm risk: at what time, according to which model • Wind gusts and feels-like temperature (hypothermia risk) • Official warnings (DWD in Germany, MeteoAlarm across Europe, NWS in the US); translate warnings in other languages on your device • Radar: our own radar for Europe (EUMETNET OPERA and DWD), NOAA in the continental US • Map with shaded relief and contour lines (Copernicus DEM) • Pressure trend from your iPhone's barometer COMPANION MODE Start it before you set out: GRAT re-evaluates the risk regularly along the way and sends a notification when it rises. No notifications are sent while the app is closed, and delivery depends on iOS and may fail. Distance and barometer measurements pause automatically while you drive. At the end of the trip you can mark whether the alerts were accurate. TO BE HONEST • GRAT does not make decisions for you; your own observation and experience always come first. • Without data the app does not say "safe" — it says "cannot be evaluated". • No alerts are sent while the app is closed. PRIVACY No account, no ads, no tracking. Your location is rounded to about 110 m. Forecasts and radar come from our own data server, which does not store your location or your IP address. GRAT PRO Core risk information (risk level, official warnings, radar) is always free. Pro adds unlimited Companion Mode (free: 2 trips per month), offline route forecasts, full history with export and the Live Activity. Monthly, yearly (14-day free trial) or a one-time lifetime purchase. Family Sharing included. Terms of Use (EULA): https://gratweather.com/terms/ Privacy Policy: https://gratweather.com/privacy/

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Unfold iPhone Duo and turn it sideways, or hold your iPhone in landscape, and the content now sits in a readable column in the middle. Lines no longer run across the whole screen. On the iPhone Duo outer screen, the first card in the Companion tab no longer touches the top edge. Winter mode, our own radar and the relief map arrived in 1.2: in snowy conditions fresh snow, snow depth and frostbite time; no avalanche rating, one tap to the official bulletin.

The developer, Bahadır CETIN, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Linked to You

    The following data may be collected but it is not linked to your identity:

    • Location

Privacy practices may vary, for example, based on the features you use or your age. Learn More

The developer indicated that this app supports the following accessibility features. Learn More

  • Supported Features

    • Larger Text

    • Dark Interface

    • Differentiate Without Color Alone

    • Sufficient Contrast

    • Reduced Motion

Seller
Bahadır CETIN
Size
6 MB
Category
Weather
Compatibility
Requires iOS 17.0 or later.
  • iPhone
    Requires iOS 17.0 or later.
  • Mac
    Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
  • Apple Vision
    Requires visionOS 1.0 or later.
  • Apple Watch
    Requires watchOS 10.0 or later.
Location
This app may use your location even when it isn’t open, which can decrease device battery life.
Languages
English and 2 more
  • English, German, Turkish
Age Rating
9+
In-App Purchases
Yes
  • GRAT Pro · Lifetime $49.99
  • GRAT Pro · Monthly $3.99
  • GRAT Pro · Yearly $24.99
Copyright
© 2026 Bahadır Çetin