The internet is a powerful tool but it never beats a little experience and a drive down to Monterey (there's never a bad reason to get breakfast in Monterey, right?). You should only use this info as a general overview of the marine conditions (it's intended for boaters not divers) and it's not what you should expect see at the specific beach site you're diving at the time you dive it. The determining factor should always be your good judgment and, of course, reports from divers still wet from their dive!

In order of reliability and relevance to the Monterey diver:

Condition Dive: This is the only real time online dive condition reporting tool. Optimized for mobile web devices, user submitted info (vis, surf, surge, etc) is parsed out by dive sites and averaged over the day. This is a free online service developed by Aquatic Discovery. The more divers using it, the more useful it is to divers!

Costal Marine Forecast: This is a great place to understand what's going to happen with surface sea conditions which can dictate which beach to check out first or where to park your boat.

Wind: The less the better. Wind kicks up wind waves which makes the surface choppy.

Wind Waves: The less the better. These waves are added to the swell when they're moving the same directions. You know these waves as the little waves that come in and make sites rough in the afternoon. If there's wind waves, diving earlier in the morning is better.

Swell: The smaller, further to the north and shorter the better. Smaller swell with shorter periods are shallower and have less energy. Since they don't reach as deep, the surge is less at shallower depths. The further to the north the swell is coming in from, the more Monterey and Carmel dive sites will be accessible (as a rule of thumb).

Monterey Bay Aquarium Bay Cam: You need to watch this webcam for several minutes to get an idea of the how the sets are rolling in and how rough the water looks. With a little imagination you can visualize what the water's doing at Macabee, Breakwater, etc.

WAM Animated Model: This cool little animated model shows what's going on out in the pacific over the next 7 days (168 hours). Keep an eye on it to see big weather systems that might be rolling in and how they'll push on local conditions. Keep in mind this model is experimental, so don't be scared off by what looks like an ugly storm system if this model doesn't jive with any of the other sources on this page.