Visit on a clear morning or early afternoon outside peak tourist season (July-August) for pleasant weather and fewer crowds.
The best time to visit the 'Old Middelburg Cathedral' (Middelburg Abbey and Nieuwe Kerk) is during a clear morning or early afternoon, especially if you plan to climb Lange Jan, as good visibility enhances the panoramic views. Visiting outside the peak tourist season of July and August will ensure fewer crowds and a more tranquil experience.
Spring (April-June) and early autumn (September-October) offer pleasant weather for exploring the complex and climbing the tower, with fewer visitors. Weekdays are generally less busy than weekends. Always check specific opening hours for the tower and any church sections, as these can vary seasonally or due to special events. Arriving shortly after opening can also help in avoiding potential crowds later in the day.