When flying, you have to wear ideal clothes for your own safety and comfort when up high in the sky. Long pants are ideal, but most of the clothing should be layered since the temperature rises during the mid-morning hours. You should wear fully-protective shoes and avoid high-heels, flip flops, and sandals.
To protect your head during takeoff, especially from the radiant heat of the burners, it’s important to wear a hat, especially during the summer. It’s not cold in the balloon when it’s flying as the radiant heat from the burner will provide some warmth. Therefore, there’s no need to suit up in winter clothes.