It can be really cold or really hot. It depends on the area. It is very rainy as well.
Higher elevations can get chilly, so sweaters and a sweatsuit for nights is a good idea.
The most important thing for this mission is shoes. You do A LOT of walking/hiking. There are uneven dirt roads. Bring a couple pairs of hiking boots or shoes.
Elders: The most commonly recommended are ECCO for boots and shoes. They have a hiking shoe (Track II Gore-Tex waterproof) that is durable and comfortable. Johnston & Murphy is also well liked.
Get good quality socks as well.
Backpacks are used in this mission. Get a waterproof one.
You need a good rain jacket or poncho.
Pretreat clothing with flea spray.
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Tips on Vaccinations like Yellow Fever and Typhoid: The cheapest options mentioned are Costco, GoodRX (request coupon), Walgreens, and County Health Department. You often have to request these vaccines and may have to pay for a travel consult. One helpful tip is to ask your doctor to send in a prescription for the vaccinations — some have had insurance cover the cost that way.
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.