Toiletries and Medical Supplies: I always forget to bring meds with me. I have been very very sick the first two times down here and have had trouble finding the meds I want, even with a local who is fluent in both Spanish and English to help me.
The lightest cloths you have in the summer and a rainjacket if you have one. Thunderstorms are fairly common in the summer afternoons and sometimes large clusters of storms can move in and last well into the following day if the steering patterens are strong enough from the northwest.
Miscellaneous: SUNBLOCK and Water by all means