Weather for Roc Mar Ton Lake, IN - Roc Mar Ton Lake, IN Weather, Current Weather in Roc Mar Ton Lake, IN. Local weather report for Roc Mar Ton Lake, IN, Local Roc Mar Ton Lake, IN weather. Forecast for Roc Mar Ton Lake, Indiana, Roc Mar Ton Lake, IN weather forecast. Find your local Roc Mar Ton Lake weather forecast. Roc Mar Ton Lake, IN weather conditions.