The prime surf season, summer is also the rainy, muggy season, beginning in June and lasting until October. Water temps are in the 80s; air temps in the 80s and 90s. Most surfers visit Mexico in summer.
This is when the booming south swells begin to taper off, but there is still plenty of action, especially at the beach breaks. Temperatures cool a bit, the rain eases, the tourists go home ... but the surf is still there.
The "coldest" time of year, with air and water temps hovering in the 70s. It's pretty dry, too, and south swells are nonexistent, so the Mexican surfer instead must focus on spots that catch northwest and west swells. Not a bad time of year, but not the best.
We reckon that spring is the best time to visit Mexico because it's still dry, temps are warming up but not too much, the tourist masses have yet to arrive, and you get those early-season south swells creeping up the coast