Panama City is at sea level, so the climate is quite warm and humid (depends on the month), similar to Miami. Air conditioning is everywhere: taxis, hotels, stores, restaurants…and the locals are quite used to it. Light city clothing is recommended for Panama City. Walking the city at noon can be uncomfortable, but the early mornings and evenings are fantastic. Beach towns and the islands are warm, but a nice breeze and lower humidity on some islands makes it quite pleasant for beach goers.
The Anton Valley and Chiriqui Province are both at higher elevation and enjoy cooler weather. The Caribbean and Pacific Coasts have slightly different seasons. Because of the great variety of islands, mainland beaches, mountains and valleys, just about any time of year there is always somewhere pleasant to visit in Panama.
Here is the current Weather in Panama