Even open in the winter to?

Yes they have Fright Night and Holiday in the Park but the hours are different

Yes

Halloween and Christmas for week or two.

Yes Six Flags is open. They have special events during the different holidays.

Yew

Yez ur n Texas itz sunny all year round

Six flags is open in winter

Yez

Holiday in the Park weekends only through Christmas; Frightfest themed for Halloween in October.