Will skies be clear Tuesday night over southern Ontario?
Mostly clear skies are expected overnight, except for some high cloudiness that may be visible, caused by some high-level moisture (illustrated below for late Tuesday evening) ahead of an upper-level disturbance which is forecast to move eastward across the Great Lakes region during Wednesday.

Will skies be clear over southern Ontario Monday night?

Clearing skies are expected over most regions by (or after) sunset and by mid-evening over regions near the GTHA following a cold front that is forecast to move eastward across southern Ontario later this afternoon. Mid-level moisture (illustrated below for late evening) may cause partly or mostly cloudy skies over some regions near western Lake Ontario until late evening.

No forecast updates will be provided Friday, Saturday or Sunday.
Back on Monday April 11!

Frank

Will skies be clear over southern Ontario Tuesday night?
Skies might be mostly clear for several hours after twilight in some regions, but increasing high-level cloud will most likely be visible by about sunset. Increasing jetstream-level moisture (illustrated below for late evening) is forecast to move over southern Ontario during the evening ahead of Wednesday's low pressure trough but bright stars, Jupiter, and the otherwise clear air might cause skies to appear clear during the early evening where the increasing high cloudiness is not very thick.

Will skies be clear over southern Ontario Monday night?

Clear skies are expected overnight, caused by a strong high pressure ridge spreading eastward over Ontario with dry and cold air, while moisture and cloudiness with Monday morning’s low pressure trough move eastward from southern Ontario by sunset.

Some low clouds may develop over regions south of Lake Huron and Georgian Bay after midnight and during early morning, where some low-level moisture (illustrated below) may be present.

Will skies be clear over southern Ontario Saturday night?
Cloudy skies are expected until early morning, and then moisture is forecast to move eastward from southern Ontario (illustrated below for early Sunday morning). So, clearing skies are likely in southwestern regions before dawn while other regions of southern Ontario could see some clearing skies before dawn, except for regions south and east of Lake Huron where a northwesterly flow of cold air will help to maintain low cloudiness.

Will skies be clear over southern Ontario Friday night?
Skies may become partly clear by sunset over most regions and remain partly clear until after midnight as a weak high pressure ridge moves across southern Ontario. Lots of low and mid-level moisture is forecast to be present (illustrated below for late evening) and may cause occasional cloudy periods.