Technical details of Lake Bourget | Aix Beach spot

Spot functioning

The Traverse triggers in late afternoon when the eastern slope of the Épine massif goes into shade while the western slope (Chambotte and Revard side) remains sunny. This temperature difference creates a west-to-east breeze.

Affected area: The phenomenon is very local and mainly concerns the southern part of the lake, particularly the Grand Port of Aix-les-Bains.

Seasonal evolution:

Late June - early July: wind centered on Aix's Grand Port. As the season progresses, the wind sector shifts to end up between Aix and Le Bourget-du-Lac by early September.

Duration: The Traverse typically lasts 1-4 hours. In optimal conditions (clear weather with light west flow), it can extend across the entire lake length, from afternoon until late evening.

Unpredictability: The trigger remains mysterious and varies from year to year. Some years it occurs almost every evening, other times only 1-2 days per week.

On the water

Type: Freshwater lake, France's largest natural lake.

Depth: Great depth (up to 145m at the deepest point).

Water conditions: Generally flat to slightly choppy. During strong Traverse, waves can form.

Temperature: Cool water, wetsuit recommended even in summer.

Visibility: Good water quality.

Required level

Advanced

Spot opening date

Open all year round

Spot rideable year-round, but best conditions are in summer (June to September) when the thermal wind (Traverse) is most frequent.

The Traverse typically rises in late afternoon, between 5pm and 9pm.

Best months according to statistics: May, June and April.

Parking

Parking available at the Grand Port of Aix-les-Bains, in immediate proximity to the spot.

In summer, parking can be difficult due to tourist crowds on the beaches.

Hazards

Irregular wind: The main danger is sudden wind drop. Always bring fins as you will likely be swimming!

200-meter zone: Riding above 5 knots and jumping ONLY beyond the yellow buoys (200-meter band). This rule is strict for swimmer safety.

Launch zone: The launch area is limited and technical. Minimize time with kite in the air - immediate departures and arrivals.

Cohabitation: The spot is heavily frequented by beachgoers. Pack up your kites and lines immediately after your session. Place your foil outside the traffic area.

No rescue: No safety boat on the spot. Autonomous riding required.

Storms: Don't confuse the Traverse with storm situations which can generate violent and unpredictable gusts with no dominant direction.

Wind specificities

The spot works mainly thanks to a local thermal wind called "the Traverse", a meteorological phenomenon unique to Lake Bourget.

Traverse characteristics:

This west wind rises 2-3 times per week, usually in late afternoon between 5pm and 9pm (sometimes later). Its strength varies, generally between 8 and 20 knots, with possible gusts up to 25 knots.

Wind direction forms an arc: Southwest sector north of Aix, Northwest to the south. This direction shifts gradually throughout the summer season.

Exceptional conditions: In rare cases, the Traverse can reach impressive speeds (up to 120 km/h) and create one-meter waves.

Warning: The wind is very irregular and can stop abruptly. In South wind, conditions are particularly unstable - avoid if less experienced. In North/Northwest wind, conditions are cleaner and more regular.

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