てんきとくらす tenki to kurasu is an app that makes the popular weather forecast site "てんきとくらす" even more convenient to access. This app provides essential information related to daily life and health, such as UV index, heatstroke forecast, and laundry advice based on the season. It also includes a "Climbing Index" that helps outdoor enthusiasts assess the comfort level for mountain climbing.

The app has gained popularity among climbers, and as of August 2022, it has achieved a monthly user base of 1.3 million. The Climbing Index takes into account various meteorological conditions at the summit and foothills, providing a level-based representation of comfort for climbers. Factors such as precipitation, wind speed, and cloud cover are considered in this calculation. It's important to note that weather conditions at the summit may differ from those at the foothills.

In addition to the Climbing Index, the app also provides weather information for various recreational areas, golf courses, and the latest disaster prevention updates, including typhoons, earthquakes, and tsunamis.