Finding a sunny terrace in Bordeaux can feel like a quest, especially during the brief windows of pleasant weather that punctuate the city’s Atlantic-influenced climate. Nestled along the Garonne River, Bordeaux’s historic center is characterized by narrow, winding streets and tightly packed 18th-century buildings that often cast long shadows, leaving many outdoor cafés and restaurants in shade for much of the day. For visitors and locals alike, securing a table bathed in sunlight isn’t just about comfort—it’s part of the ritual of enjoying a coffee, glass of wine, or leisurely meal in one of France’s most celebrated wine regions.
This everyday challenge inspired a local entrepreneur to create a practical digital tool: Soleil en terrasse, a mobile application designed to show users in real time which terraces across Bordeaux are currently receiving sunlight. Rather than relying on guesswork or wandering from café to café, the app uses geolocation and solar positioning data to map sun exposure across the city’s outdoor seating areas, updating continuously as the sun moves through the sky. The goal is simple yet impactful: help people make the most of Bordeaux’s outdoor spaces by eliminating the frustration of shaded tables.
The concept resonates strongly in a city where café culture is deeply woven into daily life. Bordeaux boasts over 1,200 restaurants and cafés, many featuring terraces that spill onto sidewalks and squares, particularly in districts like Saint-Pierre, Chartrons, and near the Place de la Bourse. Yet, due to the city’s latitude (approximately 44.8° N) and the orientation of its streets—many running northeast to southwest or northwest to southeast—sunlight exposure varies dramatically not only by time of day but also by specific location. A terrace that basked in morning sun might be in full shadow by early afternoon, while another just a few meters away could remain sunlit for hours.
To address this variability, Soleil en terrasse draws on publicly available astronomical algorithms to calculate the sun’s azimuth and elevation at any given moment, then overlays that data onto a detailed map of Bordeaux’s terrace locations. The app’s developers collaborated with urban planners and accessed municipal databases of licensed outdoor seating areas to ensure accuracy. Users can view a color-coded map: terraces in direct sunlight appear in warm yellow or orange, those in partial shade in lighter tones, and fully shaded areas in cooler hues. Tapping on a specific terrace reveals the name of the establishment, its address, and an estimated duration of current sun exposure.
The application launched in beta form in spring 2023, initially covering the historic center and expanding gradually to include neighborhoods like Bacalan and Les Quais. According to its creator, who spoke at a local tech meetup in Bordeaux in June 2023, the idea emerged after repeatedly failing to find a sunny spot for her morning coffee despite checking multiple cafés. “I realized I wasn’t just wasting time—I was missing out on the simple pleasure of being outdoors in a city that’s beautiful when the sun hits its limestone façades,” she said. The feedback from early users has been overwhelmingly positive, with many noting they now plan their outings around the app’s recommendations.
Beyond convenience, Soleil en terrasse touches on broader themes of urban livability and climate adaptation. As cities worldwide grapple with rising temperatures and shifting weather patterns, tools that help residents optimize their leverage of public and semi-public spaces are gaining attention. In Bordeaux, where summer heatwaves have become more frequent—Météo-France recorded 18 days above 30°C in 2022, compared to just five in 2000—knowing where to find shade or sun at a given moment can influence comfort, energy use (e.g., reducing reliance on indoor cooling), and even social interaction patterns.
The app also supports local businesses by increasing visibility for terraces that might otherwise be overlooked due to poor sun exposure at certain times. A café tucked into a north-facing alley, for example, may struggle to attract afternoon customers despite offering excellent service. By highlighting when its terrace does receive sunlight—perhaps mid-morning or late afternoon—Soleil en terrasse helps distribute foot traffic more evenly across the city’s hospitality sector. Some establishment owners have reported noticing upticks in visitors during previously slow periods after being featured in the app.
How the Technology Works
At its core, Soleil en terrasse relies on a combination of open-source solar calculation libraries and custom-built mapping tools. The app uses the NOAA Solar Calculator algorithm—a trusted model used by meteorologists and astronomers worldwide—to determine the sun’s precise position in the sky based on latitude, longitude, time, and date. This data is then processed alongside a geographic information system (GIS) database of terrace footprints, which includes not only their location but also their orientation, surrounding building heights, and potential obstructions like trees or awnings.
To build this database, the development team partnered with Bordeaux’s municipal urban planning department, which maintains records of all authorized outdoor seating installations under the city’s réglementation des terrasses. These regulations, updated most recently in 2021, govern everything from terrace size and placement to materials used and hours of operation. By accessing this official data—made available through Bordeaux’s open data portal—the app ensures it only features legally sanctioned terraces, avoiding private or unauthorized setups.
Real-time updates are powered by the device’s internal clock and GPS, eliminating the need for constant server communication and preserving user privacy. No personal data is collected or stored; the app functions entirely on-device after the initial map download. This design choice reflects growing user concern over data privacy, particularly in Europe where GDPR compliance is paramount. The developers emphasize that Soleil en terrasse does not track user movements or share location data with third parties.
The interface is intentionally minimalist: a clean map view with toggle options for satellite or standard layout, a search function for specific addresses or venue names, and a time-slider feature that allows users to preview sun exposure at different hours—useful for planning future outings. An optional notification setting can alert users when a favorite terrace is about to lose or gain sunlight, based on their saved preferences.
User Reception and Practical Impact
Since its public release on iOS and Android platforms in May 2023, Soleil en terrasse has garnered steady adoption, particularly among tourists and remote workers who spend extended periods in the city. While exact download figures are not publicly disclosed, the app maintains a 4.7-star rating on the Apple App Store and 4.5 on Google Play, with hundreds of reviews highlighting its usefulness during spring and autumn months when temperatures are mild but sunshine is intermittent.
Users frequently mention how the app has changed their routines. One reviewer noted, “I used to walk around for 20 minutes looking for a sunny spot near Place du Parlement. Now I open the app, pick a terrace, and go straight there.” Another praised its utility during Bordeaux’s famous wine festivals and events, where crowds make spontaneous terrace hunting even more challenging. During the 2023 Bordeaux Wine Festival in June, local tourism offices reported increased inquiries about the app at visitor centers, suggesting growing awareness among international guests.
Local media have also taken notice. In a segment aired on France 3 Nouvelle-Aquitaine in July 2023, a reporter tested the app across several districts and confirmed its accuracy, noting that the predicted sun exposure matched real-time observations within a five-minute margin. The segment highlighted how such tools could inspire similar initiatives in other historic European cities with microclimate challenges, such as Bruges, Salzburg, or Girona.
From a business perspective, terrace owners who participated in a compact pilot survey conducted by the Bordeaux Chamber of Commerce and Industry in September 2023 reported mixed but generally favorable outcomes. Of the 27 establishments surveyed, 60% said they noticed an increase in weekday visitors during traditionally slower sunlit windows, while 40% observed no significant change—often attributing this to factors like menu pricing or foot traffic patterns unrelated to sunlight. None reported a decrease in customers linked to the app.
Limitations and Future Development
Despite its strengths, Soleil en terrasse faces certain constraints. The app’s accuracy depends on the completeness and timeliness of the terrace database; new openings or closures may not be reflected immediately unless reported by users or updated via municipal feeds. While the solar modeling accounts for static obstructions like buildings, it does not yet dynamically adjust for temporary factors such as parked delivery trucks, festival barriers, or large crowds that could cast transient shadows.
The developers acknowledge these limitations and are exploring ways to enhance the app through community input. A planned update for early 2024 includes a user-reporting feature that would allow patrons to flag discrepancies in sun exposure—say, if a terrace marked as sunny is actually shaded due to an unexpected obstruction—thereby improving accuracy over time through crowdsourced validation. There are also discussions about integrating weather forecast data to predict not just current sun exposure but also the likelihood of clouds or rain affecting conditions in the near future.
Longer-term, the team has expressed interest in expanding the concept beyond Bordeaux to other cities with similar urban layouts and climatic profiles. Preliminary talks have been held with tourism boards in Toulouse and Nantes, both of which have comparable historic centers and strong café cultures. However, any expansion would require securing local data partnerships and adapting the model to different architectural styles and street grids.
For now, Soleil en terrasse remains a distinctly Bordelaise solution to a very local problem—one that exemplifies how thoughtful applications of technology can enhance everyday urban experiences without overcomplicating them. By combining open data, environmental science, and user-centered design, the app offers a modest but meaningful contribution to the quality of life in a city renowned for its art de vivre.
As of November 2023, the latest version of the app (v2.1.0) includes improved map resolution and battery optimization, with no major changes to core functionality. Users seeking updates or wishing to provide feedback can visit the official website or contact the development team through the app’s support section.
If you’ve used Soleil en terrasse to find that perfect sunlit table in Bordeaux, we’d love to hear about your experience. Share your thoughts in the comments below, and consider sharing this article with friends who enjoy exploring cities one terrace at a time.