Baler's surf season runs from October to March, when the northeast monsoon (amihan) pushes consistent swells onto the Pacific-facing coast. This is the best time to visit if you are coming to surf — the waves are the most reliable, and the weather is drier and cooler than the summer months.
April to June is the hot season, with flat seas and no surf worth speaking of. The southwest monsoon (habagat) hits from July to September, bringing typhoon season — Baler sits on the eastern coast and is directly exposed to Pacific storms. Major typhoons are a real risk during this period; check forecasts carefully if visiting in these months. The Sierra Madre mountains inland provide some shelter but not total protection.
The period around December to February offers a good balance: surf is up, accommodation is easier to find than during the Christmas peak, and the weather is manageable.