It’s generally more expensive to depart on a Friday, if you have to leave on this day you can still search on Cheapflights to find great options that meet your needs.
Due to multiple factors, expect to potentially pay more when booking in January. For low rates, October can be a great choice for travel to Biarritz. Flights to Biarritz from Newark Airport in October are about $1,134 on average during October, but can be found for as low as $588.
When flying from Newark Airport to Biarritz, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.