Belize has tropical weather; which means you'll be wearing mostly shorts and t-shirts. Belmopan in particular has larger differences in temperature and less humidity than the coast, but still has relatively high humidity compared to countries further from the equator. Because of this, cotton clothing is a must. Clothing that doesn't absorb sweat will quickly become a nuisance. Belize is a pretty casual country so unless you are attending a formal business meeting, leave the ties and business suits at home. Women are not expected to wear skirts or cover their legs, so shorts are acceptable for females.