It is rainy season in Kerala right now, and it runs October to November. The rain tends to come hard and short rather than all day, and it stays warm through it — so the thing to bring is a shell you can fold into a day bag, not a coat.
Going in April
Hot and very humid before the rain, with nights that stay above 25°C.
What this means for your bag
Room for humidity
Everything stays slightly damp. Pack fewer clothes and plan to wash them, and keep anything that must stay dry in a sealed bag.
See the Summer Sun Kit packA bottle you will actually refill
Heat like this needs far more water than you think. A filter bottle also spares you buying a plastic bottle every two hours.
See the Health & Wellness packQuick-dry fabrics
Cotton takes two days to dry in this air and starts to smell before it does. Synthetics and merino wash in a sink and are wearable by morning.
See the Summer Sun Kit packA layer for indoor air conditioning
Malls, buses and restaurants are cooled far below the street, and the swing is what makes people ill. A light long sleeve doubles as sun cover and as dress code for temples and mosques.
See the Smart Casual Evening pack
Build a packing plan around the season you are actually travelling in.