Will skies be clear over southern Ontario Tuesday night?
Partly clear skies are expected during the evening, and skies will most likely be mostly clear by morning.
The frontal zone moving southward from southern Ontario during Tuesday afternoon will likely have lots of high, mid and low-level moisture remaining over southern Ontario during the evening and the moisture (illustrated below for high-level and low-levels during Tuesday late evening) is forecast to gradually move southward from southern Ontario overnight.

Will skies be clear over southern Ontario Saturday night?
Mostly clear skies are likely over most regions, except for some periods of partly cloudy skies caused by some upper-level moisture (illustrated below for late evening) which is forecast to move over southern Ontario overnight. High clouds caused by the moisture should be easily visible in the bright moonlight.

Will skies be clear over southern Ontario Friday night?
Mostly clear skies are expected overnight. Some low scattered clouds that may be visible at sunset ought to be gone by the end of twilight.

Will skies be clear Tuesday night over southern Ontario?
Mostly clear skies are likely, except for some thin high cloud that will probably be visible over some regions, caused by jetstream-level moisture (illustrated below for late evening) which is forecast to gradually move south of Ontario overnight.

Will skies be clear over southern Ontario Friday night?

Clear skies are expected, except for some high-level thin cloud over the GTA during Friday that might be visible during the evening under the bright moonlight. The high jetstream-level moisture is forecast to move eastward from southern Ontario overnight (illustrated below for late evening) but might cause some high-level cirrus to be visible at sunset from the GTA and northward. 

Will skies be clear Thursday night over southern Ontario?

Clear skies are expected (no details necessary).

Will skies be clear over southern Ontario Wednesday night?
It looks like Wednesday's cloudiness is forecast to move eastward by evening, leaving mostly clear skies overnight. Some low-level cloudiness that develops during the afternoon may take until twilight to dissipate (low-level moisture illustrated below at sunset). By early morning, some mid-level moisture is forecast to move over southwestern regions (illustrated below at morning twilight) and may cause some mid-level clouds.