Will skies be clear over southern Ontario Thursday night?
Partly clear skies are expected over eastern parts of southern Ontario due to some low-level clouds that may appear during the evening (caused by low level moisture, illustrated below for late evening) and mostly cloudy skies are expected over western regions during most of the night (caused by mid-level moisture over southwestern Ontario, illustrated below for late evening).

Skies are likely to become mostly clear by early evening, except for some regions where some low or mid-level clouds may appear, due to low and mid-level moisture remaining over southern Ontario after sunset (illustrated below for late evening). Then, increasing cloudiness (not illustrated) is expected before morning twilight.

Will skies be clear over southern Ontario Tuesday night?
Mostly cloudy skies are likely, due to low-level moisture as well as jetstream-level moisture forecast to be over southern Ontario (illustrated below for late evening) but some breaks in the low cloud cover over some regions from time to time may allow bright moonlight to give the appearance of partly clear skies.

Will skies be clear over southern Ontario Saturday night?
Mostly clear skies are expected, but some mid-level and high-level cloudiness is likely to appear over most regions from time to time, due to jetstream-level moisture over southern Ontario (illustrated below for the sunset hour) and due to mid-level moisture which is forecast to move across some regions of southern Ontario (illustrated below for late evening).

Will skies be clear over southern Ontario Friday night?

Mostly clear skies are expected, with a high pressure ridge and dry airmass moving over southern Ontario, except that some jetstream-level clouds could appear occasionally, due to the jetstream over southern Ontario overnight (illustrated below for late evening), as well as occasional low-level clouds that may appear from time to time until the moisture (moving eastward during Friday afternoon) is completely replaced by dry air.

Sunday April 2: no updates will be posted today but increasing cloudiness seems very likely for Sunday evening over southern Ontario.

Will skies be clear over southern Ontario Saturday night?
Skies are likely to be clearing by about sunset, and some low and mid-level clouds are likely to be visible from time to time overnight as a result of moisture which is forecast to be over southern Ontario (illustrated below for late evening).