The iAtmos app is an open source project for crowdsourcing weather data on iOS devices funded by MYGEOSS EU project. The iAtmos app utilizes any available sensor found on an iPhone device (e.g. pressure sensor) for collecting weather related sensory input. Additionally, users can manually enter their own observations about both current and future weather conditions. The collected data is clustered by location, centrally processed, and loaded back into the iAtmos app for informing mobile users about weather conditions in places of interest.