I visited Meteora on a Friday in early October 2019. After a night and morning of heavy rainfall, the air was clear, allowing for some great views. The WHS fulfills five of the ten selection criteria, both cultural and natural. And indeed the monasteries are architectural and technological masterpieces of human creative genius in an area of exceptional natural beauty.
One should beat the (bus) crowds by arriving here early. I highly recommend staying in the area for one or two nights (Kastraki is nicer than Kalampaka, and even the locals go to Kastraki for dining). And I would avoid the peak season in summer. Parking is free but quite limited given the huge crowds. The monasteries of Varlaam and St. Stephen’s have the most parking spots.
Due to the opening (respectively closing) times of the monasteries, I managed to visit four of the six inhabited monasteries on that Friday. In total there are 24 monasteries and hermitages. The admission prices are fair at 3 EUR per adult, per monastery. There are no combination tickets available. All four monasteries were worth visiting for their amazing church interiors and viewpoints. Photographing is prohibited within the churches. I started with Roussanou, continued with Great Meteoron, where it got really crowded around 13:30, and finished with Holy Trinity (most exhausting access with a rather long walk downhill, followed by 150 stairs up but overall manageable) and St. Stephen’s, the only monastery that can be reached without having to climb stairs.
The opening hours of the six inhabited monasteries are as follows (as of October 2019):
St. Stephen’s - Summer (1 April - 31 October) 09:00-13:30 and 15:30-17:30, closed on Mondays; Winter (1 November - 31 March) 10:00-13:00 and 15:00-17:00, closed on Mondays.
Great Meteoron - Summer 09:00-15:00, closed on Tuesdays; Winter 09:00-15:00, closed on Tuesdays and Wednesdays.
Roussanou - Summer 09:00-17:00, closed on Wednesdays; Winter 09:00-14:00, closed on Wednesdays.
Holy Trinity - Summer 09:00-17:00, closed on Thursdays; Winter 09:00-16:00, closed on Wednesdays and Thursdays.
Varlaam - Summer 09:00-16:00, closed on Fridays; Winter 09:00-15:00, closed on Thursdays and Fridays.
St. Nikolaos Anapafsas - Summer and Winter 09:00-16:00, closed on Fridays.