Ayutthaya in May

November through March offers the best weather with temperatures around 25-30°C and minimal rain. December and January are peak months when the ruins look golden in the dry season light. But crowds are thickest then too. April gets brutally hot - we're talking 35°C+ with humidity that makes cycling miserable. The rainy season from May to October brings afternoon downpours that can flood the lower temple areas. Here's what most guides won't tell you: early morning in any season beats midday. The temples open at 6 AM when it's cooler and the light is softer. Sunset at Wat Chaiwatthanaram happens around 6 PM in winter, 7 PM in summer.