I don't worry about humidity or cold. Humidity out here in the damp pacific north west is like... well raining... or in the upper 60 at the peak of summer heat when it reaches about 80F. Plus mine get plenty of ventilation.. they sleep outside by choice.
If you don't get single or teen digit weather for extended times, you really don't need to heat coops. Then they might get chilled when they walk out and some say heating the coop increases chance of frost bite when birds do go out. Just don't let water build up on walls inside and they should be fine. Humidity here is 89% today.

If you don't get single or teen digit weather for extended times, you really don't need to heat coops. Then they might get chilled when they walk out and some say heating the coop increases chance of frost bite when birds do go out. Just don't let water build up on walls inside and they should be fine. Humidity here is 89% today.