The research is aimed at developing a mobile application for calculating atmospheric air temperature using a wet thermometer. The use of an improved mobile application is the main tool for users to calculate the atmospheric air temperature using a wet thermometer. The mobile app helps users get results anytime, anywhere. The mobile application is designed for users who want to calculate the temperature of atmospheric air using a wet thermometer. When developing the mobile application, the Xcode platform was used. The mobile app is developed in three main languages. Kazakh-speaking users, as well as Russian-speaking and English-speaking users. The mobile app includes many features such as explanations, calculations, the ability to calculate simultaneously, and the ability to change the language to be understandable to users. The mobile application, the wet thermometer, atmospheric air.