We were there in mid-October last year. Temps were low to mid 80's during the day and would drop into the low 60's at night. All we wore short & t-shirts, even in the evening & were plenty comfortable. I did think the mornings were a bit cool, but it warmed up so quickly during the day, that I never bothered with a jacket.
It has been a lot more rainy than usual this year, so temps might get cooler in Oct. A pair of pants & a light jacket might not be a bad thing to pack, just in case.
Hope this helps.