I've reflected on the subcomments I've received. Evidently there's a consensus of sorts that the whole northern part of Spain is "northeastern Spain", even if the northern part is on the Atlantic and the southern part is on the Med.

That's fine - it seems to be about the semantics of "northeast", which I don't care to take a stand on. So I yield.

I'm looking at a map! The eastern border of Spain is the pyrenees, and Catalonia lies at the south end of the pyrenees; it as far south as you can go, down the eastern border. North-east Spain lies on the Bay of Biscay; South-east Spain lies on the Mediteranean.

The north-east portion of Spain is the Basque country. That does lie on the Bay of Biscay.

I agree that Catlunya is north of e.g. Madrid, or Grenada, or whatever. But Catalunya is certainly the southernmost part of eastern Spain. Saying it is "the northeast of Spain" is just wrong. Hell, look at the wikipedia link that sibling posted: it's as clear as daylight. You can't go further east without arriving in France; but you can leave Catalunya through it's northern border, without leaving Spain.

Catalunya is therefore not "the northeast of Spain".