For setting opening_hours, I like https://projets.pavie.info/yohours/, which forwards to https://openingh.openstreetmap.de/evaluation_tool/?EXP=Summer%2008:30-19:00;%20Winter%2009:00-16:30 for more complex cases.
In this case here, I settled on `opening_hours=Jun-Aug 08:30-19:00; Dec-Feb 09:00-16:30`.