Karak sits at around 1,000 metres on an exposed ridge, so the seasons are sharper than you might expect for the Middle East. Spring (March–May) and autumn (September–November) are best: mild days, cold mornings, and the wadis below the town green up briefly. Summer can be hot at midday but cools dramatically after sunset; winter brings rain and occasional snow that closes the castle for a day or two at a time.
The Friday weekly market is the liveliest day for the old town. Avoid arriving late in the afternoon during Ramadan — most restaurants are shut until iftar.