Will skies be clear over southern Ontario Thursday night?
Mostly cloudy skies are expected, due to lots of high clouds, but skies may become mostly clear for several hours during late evening and around midnight over regions north of Lake Erie where mid and high-level moisture diminishes before increasing again before morning (illustrated in the total cloud cover chart shown below).

Will skies be clear over southern Ontario Wednesday night?

Mostly clear skies are expected, except for some scattered low cloudiness that may appear especially over regions east of Lake Huron and Georgian Bay.

Will skies be clear over southern Ontario Tuesday night?

Partly clearing skies are expected over most regions, except for lots of cloudiness over regions south and east of Lake Huron and Georgian Bay, especially during the evening (illustrated below with low-level moisture during early evening). Less cloudiness is likely later in the night as winds back to southwesterly and lake-effect cloudiness diminishes over regions south of the lakes.

Will skies be clear over southern Ontario Saturday night?
Partly or mostly clear skies are likely over some regions during the evening, except for occasional cloudiness over some regions due to varying amounts of low and mid-level moisture that is forecast to move over southern Ontario, and then increasing high-level cloudiness is expected especially after midnight.

Will skies be clear over southern Ontario Friday night?

Partly clear skies are likely with lots of lake-effect cloudiness over regions south and east of Lake Huron and Georgian Bay.

Will skies be clear over southern Ontario Wednesday night?

Mostly cloudy skies are expected, due to lots of moisture flowing southeastward from Lake Huron and Georgian Bay, except that clear breaks may develop occasionally over some regions and allow stars to appear and give the appearance of clear sky.

Will skies be clear over southern Ontario Monday night?

Clear skies are expected over most regions, except for southwestern regions where moisture flowing southward from Lake Huron (illustrated below for early evening) will maintain mostly cloudy skies over those regions, and except for some low clouds remaining over some regions for several hours after sunset.