Been my finding that walleyes eat/bite all day if you can find them, troll troll troll or drift with a jig, location is key, sometimes eyes will be in a spot that you could never guess. Walleyes seem to feast especially during the post spawn-flats/weedbeds/ even off- shore reefs can be hot, early fall-structure, and right after first ice just about anywhere. Most lakes walleyes will move in at dusk/dawn during the low light periods chasing fry into the shallows for easy pickings, easy for them and easy for you to find the eyes. Slipbobs suggestion of going to the transitional zone where a steep dropoff is a good bet in the fall. Offshore reefs can also be loaded with eyes in the fall.
Clear water on a bright sunny day tends to push them deep although in stained/cloudy water they can stay in the shallows all day, depends on your circumstances, and wind is always good "walleye chop". I was always told to fish walleye late at night but have found over the years that you can catch them at any time of day.
Walleyes seem to be able to adapt to all kinds of circumstances, on a local lake I fish, I have caught eyes literally everywhere on the lake... from right on shore on a sunny 90 degree day to the deep holes on a cloudy cool day.
Baits I love to search with, My top search lures;
Fast 1-4mph: Trolled Thundersticks, Rapalas, Slow 0.1-2mph: Night Crawler Harnesses.
But give me a jig-n-crawler any day.
For smaller eyes think finesse... light line, light as jig as you can get away with, for big walleyes think BIG for a 30" fish a #13 rapala or #9 spinner blade is not to big.
-Scott
One more question... the whether. If it's cloudy will the walleyes tend to bite all day? Will the afternoon bite be as good?