What to actually pack for late May given the monsoon and temple dress codes

Late May is the start of the southwest monsoon on the south and west coasts, so pack a foldable waterproof jacket or poncho even though most days are still warm and sunny between showers. Layers matter: it is hot and humid at the coast but genuinely cool in the hills (Nuwara Eliya, Ella, Horton Plains at dawn), so bring one light fleece/long-sleeve. For temples, a single lightweight scarf or sarong is enough; throw it over shoulders and knees on entry and remove shoes and hat. A backpack beats a suitcase here because of trains and rough pavements.