Old City (Rattanakosin) in May

November through March is golden hour for temple hopping — clear skies, manageable heat, and those Instagram-worthy sunsets over Wat Arun. December and January bring the crowds though. Chinese New Year in February means temple ceremonies you won't see any other time, but also means packed boats and longer queues. March starts getting sticky, but you'll have the places more to yourself. April through October? Look, the temples don't close for rain, but trudging between Wat Pho and the Grand Palace in 95-degree heat with 80% humidity isn't anyone's idea of fun. If you must visit during rainy season, go early — 7am temple visits before the heat kicks in.