No, it's a relatively lousy time to go.  The Sea of Cortez is
considered cold-water diving at that time of the year, as water temps
will be in the 60s and viz will be limited.  If that's OK with you,
and you can find a dive op going out, then you'll be rewarded with
cooler air temps.  Cortez Club has an onsite dive op with small fast
boats.  It's a couple miles from town, close enough for a quick cab,
it's cheap, and I know a lot of people that have stayed there and
enjoyed it.  Cantamar, the only other "resort" with an onsite dive
shop AFAIK, is about 10 miles from town and I don't recommend it
personally, nor do a lot of the people I know who now stay at Cortez
Club.  There are also plenty of hotels in town where you could hook up
with one of several dive ops in town, but I'm not informed much on any
of them.