Summers are hot and humid. Temperature around 70°F to 95°F (21°C to 35 °C). Usually blue sky but could also rain.
Definitely bring you bathing suit. Most apartment complexes and hotels have a pool, it is easy to find indoor and outdoor public swimming pools, and the beach is at a 2.5h drive.
Public transportation is very limited, buses are difficult to navigate when you're coming from outside of downtown. There is a free R line bus that drives around downtown to help you get to different locations. The most common way to travel is by car but you will find tons of Uber/Lyft taxis, Bird/Lime scooters and Lime bikes. In downtown Raleigh you can walk to most places.