The entire time you are in Costa Rica it is going to be humid. I stayed in an AirBNB in which the bedroom was air conditioned but the living space was not. When I woke up in the morning it was like two very different seasons. I put my glasses on and they got completely fogged up when I went into the living room.
If you are a germaphobe like me, it is a two shower a day type of place. In fact, two of the days I took a shower before bed and then when I woke up in the morning. Expect to sweat in your sleep and feel sticky all the time. If you are choosing an AirBNB or hotel make 100% certain that you choose something with air conditioning. I don’t know how anyone could enjoy a vacation without air conditioning.