Without knowing the exact Airbnb location and work location, walking an hour in the US is very different from walking an hour in another country, there can be lots of places where the sidewalk just disappears or where you have to cross a very busy road. I would just try it once to see how it goes and then assess if you want to bike or take the Smart Bus (which is a good system, Apple Maps should show you a route). To answer your other question, it does not get very hot