Were they all wearing short sleeves? You'd think they'd know better by now.
Tyreese had a long sleeved shirt with the sleeves rolled up. Michonne is sleeveless as usual (except when she had her pirate shirt), Glenn is starting to dress like Prison Rick, and Rick was in a T-shirt. They usually wear jackets at the beginning and end of the season because of the colder weather, but for a majority of the season being shot in the summer and early fall, its still HOT in Georgia.