The construction of the viaduct of the Nouvelle Route du Littoral, connecting Saint-Denis to La Grande Chaloupe in La Réunion, is particularly challenging in terms of the wind environment. In addition to being built in a cyclonic region, the 5.4 km long viaduct is being built in open sea, 100–150 m from the coast. The gust wind speed can reach up to 64 m/s at deck level during a cyclonic event. The height (10 m) and length (270 m) of the double truss launching girder make it particularly sensitive to turbulent wind and induce significant additional wind load on the viaduct and the cantilever under construction during a cyclonic event. The 120 m span and relatively large width (28 m) of the deck also play an important part in the dynamic response of the whole structure. This paper presents how the local wind conditions and the aerodynamic properties of the deck and the launching girder were determined. The methodology used to perform the time history simulations of the viaduct during the construction phase are then described, as well as the main results for the studied configurations.