It is hot and humid all year round.
You only need a sweater or two, but the rest of your clothing should be light-weight, quick drying, and breathable.
Elders prefer Serve shirts or &Collar. Cotton is too hot. No need for a suit coat.
It also rains quite a bit, so a poncho or a light-weight rain jacket is needed.
Make sure bags are waterproof as well.
Carrying handkerchiefs can be nice to wipe off the sweat.
This is a walking mission, so get GOOD shoes that are comfortable, that are already broken in, and will hold up. Buy a couple pair and rotate them every day. Several people recommend ECCO shoes for Elders.
They sleep in hammocks.
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Serve shirts have a ventilation panel in the side of the shirt making them noticeably more breathable. Missionaries serving in hot or humid places absolutely RAVE about this feature. The most popular shirt for hot-climate missions, for sure.