Should I stay in Irbid?

If Umm Qais and the far north are a real focus, yes. If you only have one northern day, Jerash and Ajloun from Amman are the usual pair.

What's the walking like?

Highland tracks and site walking, greener than the south after rain. Not canyoning, not diving.

A couple of hours, more with traffic. It's a committed north day, not a half-hour hop.

Is it good in summer?

Better than the rift floor, still hot. Early starts and the same water discipline as anywhere inland.

Things to do in Irbid

Irbid is the northern university city and the jump toward Umm Qais and the Yarmouk. It's quieter than Jerash on the tourist circuit and further from Amman. You'll come if the far north is the point, not as a default first night after landing.

Highland walks toward Umm Qais

Walking here is highland and viewpoint country, with Roman and Ottoman stone at Umm Qais. It's still not Rum. Treat it as a north-of-Jerash extension. Open the Book here tab if a trip actually meets in Irbid. Many northern days still start in Amman.