The high humidity should be leaving thanks to the low pressure system that crossed today and has brought showers and thunderstorms since Wednesday afternoon/evening. However temperatures will remain above normal (with some humidity) until another front crosses Ontario late Saturday and brings in a little cooler air for Sunday.
Temperatures will bounce around a couple days next week with Monday to Wednesday being above normal before a low pressure system arrives Wednesday with much cooler air behind it.
See below from the GFS model for the temperature departures from normal:
This means temperatures in the high teens since normal is around 21c. Some models are hinting that the cooler air sticks around for a week or two, while other models have above normal temperatures returning sometime around the 16-19th. My feeling is things will warm up to normal to slightly above.
Here is the long range for the next 15 days from the NAEFS model which highlights a chance of slightly to above normal for most of Southern Ont.
Also there is some potential in the tropics that could develop into another tropical storm or hurricane that should be watched for next week, but confidence is only around 60% chance of development.