It's 2pm on an April Saturday in Brussels. The sun breaks through the clouds. You're looking for a terrace to have a coffee - but which one is in the sun right now ? Not in an hour. Not "in general". Now.
That's the problem that Sunny Terraces solves. A web app that shows, on an interactive map, which terraces in Brussels are getting sun at this exact moment.
The problem
Brussels has hundreds of terraces. Google Maps tells you which ones exist and whether they're open. But it doesn't tell you if a terrace is in the shadow of a building at 4pm, or if the sun is beating down on it at noon.
Weather apps tell you if it's sunny in general. But "sunny" in Brussels doesn't mean your terrace is in the sun. Orientation, surrounding buildings, time of day - all of that changes things.
There was no tool to answer this simple question: "Where can I sit in the sun, right here, right now?"
The concept
Sunny Terraces combines several data sources to answer this question in real time:
- ☀️ Sun position - The app calculates where the sun is in the sky at any given moment (azimuth and altitude), based on the time and date.
- 🍽️ Brussels terraces - All the terraces of cafes, bars and restaurants in Brussels are listed, with their exact position and orientation.
- 🗺️ Interactive map - A Mapbox map displays the terraces with a color code: orange for "in the sun", gray for "in the shade".
- ⏰ Time simulation - A slider lets you see which terraces will be sunny in 1h, 2h or 3h. To plan ahead.
- 🌦️ Real-time weather - Cloud cover is factored in to give realistic information. If it's overcast, no terrace is "in the sun".
- 🌍 Multilingual - The interface is available in French, Dutch and English - the three languages of Brussels.
The user experience
On mobile, the app is designed for use on the go. The map takes up the whole screen. A floating header displays the weather and controls. A panel at the bottom lets you filter by type (cafe, bar, restaurant) and adjust the time.
When you tap a terrace, a card appears with the name, address, opening hours and a direct link to GPS navigation. Photos and reviews are included to help you choose.
On desktop, the same information is presented with a sidebar on the right showing filters and details. The map stays centered.
Tech stack
The project uses a modern, fully frontend stack:
The solar calculation algorithm, facade detection and filtering logic are entirely client-side. No custom backend, no server to maintain. Technical details will be published once the project goes live.
Where does the project stand?
Sunny Terraces is under active development. The core features are in place:
- Interactive map with all the terraces in Brussels
- Real-time sun calculation with color coding
- Time simulation (move forward/backward in time)
- Filters by venue type
- Detailed cards with photos and reviews
- Mobile-first responsive interface
- FR / NL / EN support
What's left to do:
- Performance optimizations
- Progressive Web App (mobile installation)
- Terrace sharing via URL
- Native iOS app
- Large-scale user testing
Eventually, a native iOS app is also being considered to offer an even smoother experience - background geolocation, notifications, and quick access from the home screen.
The article will be completed with technical details once the project is publicly launched. Stay tuned.