Bangkok changes significantly by season — here's exactly what to bring depending on when you visit.
Light layers for evenings (it can feel cool!); sunscreen still essential; no rain jacket needed; one umbrella just in case; light trousers comfortable.
Lightest possible clothing; high-SPF sunscreen; hat; sunglasses; electrolyte tablets; portable fan useful; sandals better than closed shoes in heat.
Compact umbrella or rain poncho daily; quick-dry clothing; waterproof phone case; accept that you will get wet sometimes; river levels rise — factor into boat tour plans.
Modest clothing for temples (shoulders and knees); 1 nicer outfit for upscale dining; comfortable walking shoes that can take moisture.
Cheap laundry services (by the kilo) are available across the city, so packing light and washing every few days works better than over-packing for a long trip in the heat.
Many Bangkokians dress more formally than visitors expect, especially in offices and malls — a couple of smarter pieces help you blend in for nicer restaurants or business settings.
February through April can bring elevated air pollution from regional burning — a light mask is worth packing if visiting during this window and sensitive to poor air quality.