I often pitch substitute teaching. Not traditionally "seasonal", but you can pick the days (months, weeks, whatever) that you work and those you don't and you never have to ask to have a specific day off. If you only want to work 6 months, as long as those aren't during the summer (although there are summer school subs as well, but there's not much need), decide what months those are and only make yourself available.
Generally requires a college degree and then whatever test or other requirements your local area has. And you can sign up for more than one district if that geographically feasible.
Biggest downside is that it's not entirely predictable or reliable, especially at first. If you are good, you'll get lots of requests, but that takes time to build up.