OpenWindow.live answers one question in real time: should you open your windows right now?
The decision is based on your exact location's live outdoor conditions — temperature, humidity, and air quality index — compared against your indoor temperature preference. No general advice. No weather app to interpret. One direct answer.
When you open the app, it fetches live outdoor data from OpenWeather and AQICN for your precise coordinates. Five rules are applied in order:
You can adjust your indoor temperature reference and allergy/pollution sensitivity in the settings.
Opening windows at the right time can reduce indoor temperature by 2–5°C in 30 minutes — without air conditioning. With European summers setting new heat records every year and growing awareness of indoor air quality post-2020, we wanted a tool that gives a direct answer rather than raw data to interpret yourself.
The idea came from noticing that millions of people search "when to open windows", "Lüften wann", "quando aprire le finestre" every summer — and finding only articles, never a live tool.
OpenWeather provides real-time temperature, humidity, and wind data updated every 10 minutes. AQICN (World Air Quality Index) provides the air quality index from the nearest monitoring station. Data is cached at our Cloudflare edge for 5 minutes to reduce API load and improve response time.
The climate tables on city pages and in our guides come from the Open-Meteo historical archive: hourly temperature and humidity for 2021–2025 and hourly PM2.5 for 2023–2025 (air-quality values are estimates from the European CAMS model), averaged by month and by local hour for each city. Nothing in those tables is typed by hand.
The heating-cost calculator uses standard physics: warming 1 m³ of air by 1 °C takes about 0.34 Wh, and we assume that one short, wide-open airing replaces the air of the home once. Heat stored in walls and furniture is not counted. If you spot an error, write to us and we will correct it.
Your location is never stored on our servers. All preferences (indoor temperature, sensitivity setting, temperature unit) are saved only in your browser's local storage. No account needed. No email required. No personal data collected.
See our full Privacy Policy for details on third-party services and cookies.
The app is available in English, Italian (Italiano), Spanish (Español), German (Deutsch), French (Français), and Portuguese (Português). Language is auto-detected from your location when you first visit.
Questions, feedback, or data accuracy reports: info@openwindow.live