Absolutely.....until the ice forms, then you're cold like everyone else.

Toronto Islands benefit from both the Toronto heat island and Lake Ontario but winter N, NW, or NE winds don't warm up a whole lot by going over 1.5km of water and they won't warm up at all if the lake is frozen.

That said, I have a clump of showy red glads that have survived 5 years (Kingston, ON) though the lack of snow this year may have cut them back a bit. So growing glads in warmer areas of southern Ontario may not actually be very difficult.

Even in the winter if ice forms, you will find that low temperatures are moderated within a mile or so of large bodies of water as compared to inland locations. This is why you typically see a narrow band of a warmer zone along the shores, particularly the leeward shores, of the Great Lakes.

Hi,
I'm in Toronto beaches and that makes my area Canadian Zone 6b. I noticed that compared to downtown it's a little cooler by the lake in the summer and a little warmer in the winter.

From the Toronto Gardens blog:
"In Canadian terms, Toronto is broadly Zone 6; in USDA terms, it's Zone 5. Our closeness to the Great Lakes moderates temperature highs and lows and increases precipitation.

Within the GTA, the specifics of your landscape can push you higher or lower. Close to Lake Ontario, you're more likely to be Zone 6b and might have a microclimate (a pocket that is a zone unto itself) that's Zone 7. In a more exposed situation, or farther from the lake, you might be Canadian Zone 5a or 5b."

That being said, I don't think it makes a huge difference in our plant selections. Climate change is scary but it we had a great winter, didn't we:)

I think it does in one way, and not in another if that makes any sense. We're across the water from you on the NY side of Ontario. We always talk about the "invisible line" that exists here in the spring especially-you can drive from about 10 miles away and go from "omg it's SOOOO HOTTTT" to "uh, where's my sweatshirt". The "line" does seem to move. Earlier it was about 2-3 miles inland, then about a week ago it seemed to go through our backyard (we're directly on the lake). I noticed my plants bloom about 1-3 weeks behind others that are more inland. I also noticed that plants that aren't supposed to do well here do. There's a specific lavender, I'd have to look it up, that isn't supposed to be hardy here and it's grown HUGE at our cottage! In fact, it's sending up flowers right now :) So..I think it throws the seasons off a little, but they are still about the same-just a little later.