- OMSZ Meteora
- Onde
- ONDO Weather
- OnlinePro
- Ontario Air Quality
- OnTheSnow Ski & Snow Report
- Ontoto Connect
- Alarma Rayos
- OPEN I-STORMS
- OpenSnow: Weather Forecast
- OpenSprinkler
- OpenSummit
- OpenWeather
- OpenWind
- IBM Dashboard Visualization
- OPM DC Status
- OPU ENV Sensors Monitoring
- OPUS ONE SMART UMBRELLA JONAS
- Orai Lietuvoje
- ORBIS COMFORT CONTROL
- Orbit: Posición del Sol
- Orbiter - Earth Visualizer
- OregonAir
- OrientElba
- OSHA-NIOSH Heat Safety Tool
- OSS Weather
- Oto App
- OurTheEarth:Genuine Earth as viewed from space
- Outside Now
- Overdrop - Clima y widgets
- Owl Weather
- Oz Radar 2
- Oz Radar Lite
- Oz Radar TV
- Oz Radar Weather
- Oz Weather Plus
- OzSun UV Alert
- O’Colly