The weeks of the annual summer vacations are the usual peak seasons for tickets anywhere. Another high season would be the months of November or December, as those are the months when a lot of people, including OFWs, fly back to the country to be with their families during the Christmas season. May might qualify as part of the high season, because summer vacation in the Philippines starts at the end of March and ends at the beginning of June. If you want a non-peak season, I may recommend that you visit the country during the months of July or August. EDIT: @ Xander, ouch, wrong is such a strong word. Thanks for the Thumbs Down.