Rain Alarm Extension is a weather tool designed for Firefox that provides real-time alerts for impending rain. Unlike typical weather forecasts, it utilizes almost instantaneous data from governmental weather services to notify users when rain is approaching. This makes it an invaluable companion for outdoor activities such as cycling, hiking, and biking, ensuring users can plan their outings without unexpected weather disruptions.

The extension supports a wide range of countries across the Americas, Europe, Asia, and Oceania. Users from regions including the USA, Canada, the UK, Japan, and Australia can benefit from its alerts. However, certain countries may not be supported due to licensing issues or lack of radar data from local weather services. Overall, Rain Alarm Extension stands out for its focus on real-time weather data and its practical application for outdoor enthusiasts.