USDA zones were developed to help people with growing plants in a
temperate climate. The vast majority of the United States (with the exception of Hawaii and southern Florida) is temperate, meaning that (1) it gets cold
enough to freeze in the winter and (2) that cold weather will last for a number of weeks or months. In the warmer parts of the U.S., plants that are resistant to frost damage can be grown all year long, other plants that are damaged by freezing weather have their season in which they can be grown. In the colder parts of the U.S., zones can be used to predict when the growing season will end in the fall and when planting can start again in the spring.
The USDA zones are
NOT useful in the tropics (within 30 degrees of the equator). In the tropics, altitude is a much more important effect than the lowest temperature of the winter, which is how USDA maps are developed. Some tropical crops cannot take the heat of low altitude, and must be grown high in the mountains. There really is no equal to the tropical, high altitude climate in the continental U.S., since that climate doesn't vary as much during the year. The U.S., being further from the equator, will have shorter days and freeing weather in the winter, even if two particular locations seem to be very similar in the summertime.
If your altitude is such that you have occasional freezes, then you can consider yourself to be in something equivalent to zone 8 or 9. I am in a transition area between zone 8 and 9; last winter was a cold zone 8, but the year before was a zone 9 winter. For the cooler half of the year, we have to grow things that are frost tolerant -- brassicas, English peas, fava beans, chicory, onions, etc. Only in the warmer half of the year can we grow corn, beans, squash, and tomatoes.
If you are low enough in altitude never to have freezes, then you are in a truly tropical climate and can look at plant guides from Florida and Hawaii for information.