Will skies be clear over southern Ontario Saturday night?
Some clear periods are likely to appear over most regions from time to time, but mostly cloudy skies are more likely to be the situation during most of the night (except for the clear breaks) due to extensive low-level moisture over southern Ontario.

Will skies be clear over southern Ontario Tuesday night?
Partly clear skies are likely to appear over many, or most, regions during the evening except for lots of high-level clouds that may or may not be visible as cirrus clouds, and except for low-level humidity that will likely cause fog in many areas. Increasing mid-level cloudiness is expected to move eastward over southern Ontario later in the evening over southwestern regions and probably after midnight near western Lake Ontario.  

Will skies be clear over southern Ontario Saturday night?
Mostly cloudy skies are expected, except for occasional partly clear skies that may be visible over most regions, but lots of low-level cloudiness, and some jetstream-level clouds, will be over most of southern Ontario during most of the night.

Will skies be clear over southern Ontario Tuesday night?
Skies will most likely become clear over most regions at some time during the evening, except for lake-effect cloudiness over many regions south and east of the Great Lakes during the early evening, and except for some high-level cloudiness that may appear over most regions caused by jetstream-level moisture which is forecast to be over southern Ontario (illustrated below for early evening).

Will skies be clear over southern Ontario Monday night?
Mostly clear skies are expected over southwestern regions west of Lake Huron, and mostly cloudy skies are expected elsewhere, due to lake-effect cloudiness south and east of Lake Huron and Georgian Bay.

Will skies be clear Friday night over southern Ontario?
Skies may appear to be partly or mostly clear during the evening, before widespread cloudiness spreads over southern Ontario by early morning, but lots of high cloudiness will be over most regions (illustrated below for late evening).

Will skies be clear over southern Ontario Thursday night?
Some high cloudiness will most likely be visible over most regions, due to jetstream-level moisture over southern Ontario (illustrated below for early evening) but skies may appear mostly clear in some regions before the moon rises and illuminates the high clouds.