Best months are Dec-March (Magic Seaweed spot guide). Check Google Flights. You can get roughly $560 flights as early as Aug 10, late as Feb 28 (Scott's Cheap Flights, Air Canada, Delta, United). Nearest airport is Toulouse, so I suspect that it might be as easy to go to Paris and take the train to Bayonne or thereabouts. Biarritz and Anglet are somewhat more accessible.

Edited: 07/09/2021 at 01:55 PM by ww