I would suggest you subscribe to some sites like
Secret Flying | Cheap Flight Deals or
YYZ Deals | Cheap Flights & All Inclusive Vacations from Toronto. Here are some current flight deals to warmer destinations;
Westjet has non-stop flights from Toronto to Bermuda from only $371 CAD roundtrip. Available from March to October (excluding summer). They also have non-stop flights from Toronto to San Jose, Costa Rica for only $367 CAD roundtrip. There is some limited availability from May to October 2018 (excluding summer). The Westjet site allows you to view prices for each week to see the deals.
Air Transit had a deal a couple weeks ago for Ft. Lauderdale in January/February 2019 for $247 CAD roundtrip (it may still be valid). That would get you down there for the Lemon Shark Aggregation.