The 2017 summer sales in France (Soldes d'été 2017) start nationally on June 28th and run six weeks until August 8th. The exceptions are departments Alpes-Maritimes and Pyrénées-Orientales that start July 5th until August 15th and on Corsica sales start July 12th until August 22nd.
Overseas departments have their own starting times independent of mainland France.
Guadeloupe - September 30th to November 10th
Guyane - September 5th to November 10th
Saint-Barthélémy and Saint-Martin - September 14th - November 24th
Martinique - September 5th to November 10th
Saint-Pierre et Miquelon - July 19th - August 29th
Réunion - Feburary 2nd to March 17th