Will skies be clear over southern Ontario Saturday night?
It looks like skies are likely to be quite clear, with a high pressure ridge over the Great Lakes region. A dry northerly flow of dry air over southern Ontario, with subsidence ahead of the upper level ridge, ought to result in clear skies overnight.

Where will skies be clear over southern Ontario early Saturday morning?

It looks like skies will be mostly clear over most of southern Ontario during the period between midnight and morning twilight, with some possible cloudiness mainly east of a line between the GTA and Georgian Bay, due a region of mid-level moisture that could appear as scattered cloudiness.

Will skies be clear Thursday night over southern Ontario?

It looks like mostly clear skies are likely as a high pressure ridge builds over the western Great Lakes region and a low pressure trough moves slowly eastward over eastern Ontario. A northwesterly flow of dry air and subsidence between the ridge and trough will be the main cause of clearing skies, and daytime low-level cloudiness is likely to diminish by (or shortly after) sunset.

Will skies be clear Monday night over southern Ontario?
It looks like mostly clear skies are likely by sunset, or shortly after sunset, as daytime cloudiness dissipates soon after sunset.

Will skies be clear Sunday night over southern Ontario?
It looks like skies will be clearing by sunset and be mostly clear overnight, primarily due to dry air aloft and subsidence ahead of an upper-level ridge that is building over the Great Lakes region during Sunday and is forecast to move over Ontario during Monday. Some cloudiness that develops during the afternoon could cause cloudy skies at sunset over some regions, but skies are likely to become clear over most regions by or shortly after sunset.

Will skies be clear over southern Ontario Saturday night?
It looks like mostly clear skies are likely by sunset, except for some mid-level cloudiness during the evening mainly near and west of the GTA and western Lake Ontario. The forecast chart below (if it loads onto the blog without complications) shows the location of the mid-level moisture during the evening. Uplift ahead of an upper level trough (moving eastward across southern Ontario overnight) will cause the moisture to form some cloudiness.

Will skies be clear Friday evening over southern Ontario?

It looks like mostly clear skies are likely, following some cloudiness during the early evening until low-level clouds dissipate.

 (Images are not posting correctly yet, but the main picture is lots of moisture at low levels, as seen in the low-level cloudiness, persisting as clouds until subsidence causes the clouds to dissipate.)