When the winds switch around to having some Easterly component (NNE, NE, ENE, E, ESE, SE, SSE) check out the wave reports. When sailboats are heading for cover due to 'Small Craft Warnings', experienced kayakers might want to head to the lake.
Forecast wave heights are generally reported in ranges.
At 1-2', generally forget it -- things are too tame to really get any surfs.
At 2-4', tame entertainment may be found.
At 3-5', you'll start catching some more worthwhile rides.
At 4-7', expect some sweet rides.
Above that, things start to get epic.
Regarding 'gauges' for the lake: While it may seem likely to check it out any time the National Weather Service issues small craft warnings, you'll quickly find that is woefully inadequate. They are generally more concerned with 'open water' rather than shore break, and tend to report exaggerated wave heights (easily double what you'll actuallly see!). The better gauge will be some websites more oriented toward board surfers, and thus reporting actual shore break wave heights. USE THIS: *
surfline.com/surf-reports-forecasts-cams-map/*
DO NOT TAKE LAKE SURFING LIGHTLY! This is a whole different challenge than the river! On the river, each feature (wave or hole) is relatively 'constant' at a given flow. On the lake, every wave changes as it heads toward shore. When waves break, they can have powerful force as the weight of many gallons of water crash down on you.
Having some sort of anti-implosion device for your sprayskirt is imperative at larger wave heights!
When waves are moderate to large, there will likely be strong currents sweeping down the shore and out toward open water. If your skirt implodes and your boat fills with water (or you are out of your boat), each successive wave will hit you, making it like trying to run (or swim) a class III or higher river with a swamped boat, but here there are NO EDDIES!
Especially any time waves are larger than 2-3' you should not boat alone. The combination of wind and waves and currents can make self-rescue far more difficult than on any river you'll encounter in the Midwest.
Wanna see what I'm talkin' about? Check it out:
Jake Ament + John McConville in Sheboygan