Jordan's second-largest city and its northern hub — younger, less touristed, and shaped heavily by Yarmouk University's student population. The main draw for visitors isn't the city itself so much as its role as the gateway to Umm Qais and the north; the archaeological museum here holds a genuinely good collection without the crowds of Amman's museums.
Irbid is about an hour north of Amman (85 km) and 20-30 minutes from both Umm Qais and Pella, which is why it functions more as a waypoint on a northern-Jordan day trip than a standalone destination.
Year-round — it's a city visit, not weather-dependent, though spring and autumn make the walk between the museum and old town more comfortable.
Most itineraries treat Irbid as a lunch stop between Umm Qais and Amman rather than the main event — it's worth budgeting an hour here if the museum interests you, but don't build a full day around it on its own.