Pickering, ON on lake Ontario's central part of Canadian shore has at least 2 surf spots:

Rouge Park beach near river outlet, with sandbar and shore break, works on SW, SE winds.
Frenchman's Bay and Beachfront Park works on strong SE, E winds.

Gavin's web cam is helpful assessing surf conditions for Toronto too.

Sauble Beach on Canadian shore of lake Huron is a great town for a vacation with nice shops and eateries on Main St. and bunch of cottages here and there. It offers great, long, sandy beach which works best on NW, SW winds. The water is refreshing even in Summer, but still, a very good surf spot. If you have issues with parking, go little bit South to Saugeen Nation beach. For current conditions see surf cam.

There more than one surf spot in Port Colborne, ON area going off on SW winds, and one of them is especially Pleasant. :-) Word of caution though: Please respect private property!!! Here is a sneak peek on how surfing may look like on lake Erie in the Summer, in the Fall, in the Winter.
Nickel Beach provides rolling shore break.
Wyldewood Beach - ideal for shortboarding.

The Grand Bend's city beach is good on its own, but it maybe worth checking the Pinery's South beach as well (even though the Pinery is a provincial park with paid access).

Wasaga Beach, ON , is very popular and crowded during Summer time and a well-known kiting and wind-surfing spot. You may see not much surfable waves from the shore as the beach is quite shallow for quite far. But Area 5 and Area 6 are known to have good waves past the last sandbar (thanks Amani!).

Hamilton, ON has a well-established surf spot on the North side of Burlington/Hamilton lifting bridge (aka The Bridge) works on E, NE winds. Unfortunately the forecast needs to be cut in half for North winds. There are good amenities (change room, shower) on Burlington side (Burlington Beachway Park) side, the sandbar on Burlington side is good for bodyboarding. See videos on how surfing at Hamilton, ON can look like in May, August, September.

Fifty Point with Kelson Beach is south of Hamilton (towards Grimsby). The sandbar works well on North, East, North East winds, conditions match nicely with Grimsby Buoy readings. If you go through conservation area gates, you'll have to pay 10 CAD. Gate hours are 7 a.m. to sunset.

I've read about numerous sandbars and shore breaks on Van Wagners beach working on E, NE had not surf there being happy with the sandy beach at the Bridge.

Web cam at Fifty Point Yacht Club is handy to eyeball current surf conditions and approximate it to all mentioned beaches. On West and South winds all spots around Hamilton are flat, so and if you see a non-zero forecast - you may ignore it.

Toronto, ON has several surf spots working at different wind directions. Watch Surf Ontario members video on surfing Toronto and vicinity in the Winter.

The Beaches may work well at E-SE and produce nice straight (but small (divide the forecast by 2) waves at strong SSW storms. I've seen some folks surfing near rocky part , but I would not dare.

The Bluffs "doublespot" can work on both, SE and SW depending what side of the Bluffers Park you take. The East Bluffers park beach shines on E-SE winds. For SW, it also works, but twice less than  the Cove (the Cliffs side) .

The other possible spot on SW wind is Cherry St. beach as Outer Harbour may have pumping waves on strong SW.

All spots may be extremely crowded at Summer time. The Beaches and the Cherry St. are official windsurfing / kite surfing spots - take that into account.

In short: