Since I've arrived in Hawaii I've been chasing the best snorkeling. The truth is that depending on where you are on the Islands then the snorkeling can vary from day to day and even hour to hour sometimes.
You know, the winter months on Oahu can get down right treacherous. Winter runs from October to around early April in the Islands. Yes, its a few degrees cooler and it rains a lot so "winter" is only a relative term, especially if you're from Massachusetts like me.
Don't Snorkel North or South in the "Winter"So, in the winter, the North Shore and West side of Oahu beaches can be dang treacherous, like I was saying. Shark's Cove, fore example, can be a calm sheet of glass with gorgeous, clear snorkeling water during the summer months and in the winter be a death trap. You just don't snorkel on the North Shore or West Oahu during the winter. Don't do it.
However, depending on weather patterns, storms (on or off the Islands), and tides the snorkel and SCUBA conditions can still be very different from day to day and (in my case) weekend to weekend.
My Go To Snorkel Conditions Report for Oahu and the Other IslandsSo, I've been using this page: http://www.hawaiiweathertoday.com/dive-and-snorkel/
Hawaii Weather Today is a pretty awesome reference point for the entire Island chain and includes sections like our snorkel and SCUBA report, surf report and a WHOLE bunch of other stuff that I don't completely understand. The guy who owns/runs it, Glenn, is a genius in my eyes and he does a thorough and extensive job.
For people like me, though, he keeps it pretty dang simple. Snorkeling conditions are either Poor, Marginal, Good or Excellent. Also, the snorkel report covers 2 days...the current one and the next and, as an added bonus, the water temperature. And the site does this for South, West, East and North shores.