Aerzeit: When to Open Windows
Open up at the right time
About
This app analyzes local weather forecasts to suggest optimal times for opening windows to ventilate your home with fresh air. It allows customization of preferred temperature ranges and filters for rain, humidity, wind, air quality, and pollen.
What's New in Aerzeit
0.11.0
August 14, 2026
City search now finds a city by its local name as well as its English one, and by any word in the name. A newly added location no longer shows weather for the wrong place before you've chosen one, and on the forecast chart, the duration labels of two short windows that fall close together no longer overlap each other. Rain chance and UV are now correct in Europe. Where a measurement is missing, those rows now show the same question-mark marker the chart already uses elsewhere, instead of the maximum. A strong wind is no longer mistaken for a missing reading, so your wind limit is respected.
MoreSubscription plans
Aerzeit Premium
Live open-window alerts. No ads. No tracking.
FAQ
What is Aerzeit?
Aerzeit is a weather application designed to inform you about the best times to open your windows for ventilation. It analyzes local forecasts to suggest optimal periods based on your preferred outdoor temperature and various environmental factors.
Does Aerzeit have ads?
No, Aerzeit is ad-free. The app is designed with privacy in mind and does not contain any advertisements or third-party SDKs for tracking.
How accurate is Aerzeit's forecast?
Aerzeit utilizes local 48-hour forecasts to provide its advisories. While it aims for accuracy, it relies on public weather data and does not model your home's specific conditions.
What environmental factors does Aerzeit consider?
Aerzeit considers outdoor temperature, rain, humidity, wind, air quality, and pollen levels. You can customize which of these filters are most important for your ventilation decisions.
Can I use Aerzeit on my Apple Watch?
Yes, Aerzeit offers a companion Apple Watch app and complication. This allows you to view the same at-a-glance status on your wrist, even when your phone is not nearby.
Is Aerzeit free to use?
Aerzeit is free to download and use with its core features. There is an optional 'Aerzeit Premium' subscription available for $9.99 per year for enhanced functionality.
How often is Aerzeit updated?
The app was last updated on August 8, 2026, with version 0.10.3. Regular updates ensure the app remains functional and incorporates any necessary improvements.
Is Aerzeit suitable for children?
Aerzeit has an age rating of 4+, making it suitable for younger users. The app provides weather information and does not contain any inappropriate content.