Basically, this is the opposite of what you might call the Winter Chicken (the chicken boss that dressed in a coat).
He wears shades and is wearing an undershirt and swim trunks. He launches eggs and sometimes, a bottle of sunscreen that squirts sunscreen in multiple directions.
At half-health, his shades fall off, and he gets angry. In case it’s not obvious, that means he attacks faster.
And yes, I figured he would appear in hot levels more often. Just as I figure it would be appropriate for winter chicken to appear in frozen levels more often.
I figure there could be another boss battle where the summer chicken teams up with winter chicken. Because why not team him up with his foil?