Will skies be clear over southern Ontario Saturday night?

Partly clear skies may develop during mid-evening as upper-level moisture and uplift move eastward. Some low-level cloudiness is likely as a result of low-level moisture (illustrated below) and lake-effect cloudiness flowing eastward from Lake Huron and this could cause partly, mostly or completely cloudy skies over southern Ontario overnight before increasing mid to high-level moisture begins to move across southern Ontario before sunrise Sunday.

Cloudy skies are likely to continue Thursday night. Although partly clearing skies are appearing during the afternoon following Thursday morning's cold front passage, an extensive layer of low-level moisture is forecast to cause continuing mostly cloudy skies over southern Ontario overnight.

Will skies be clear over southern Ontario Tuesday night?

Partly clearing skies are possible, due to a high pressure ridge spreading eastward over northern and southern Ontario with dry air and subsidence that may cause the cloud layer over southern Ontario to subside and result in partly clear skies in some locations. However, the substantial layer of moisture is not likely to subside and disperse easily, and probably will remain as a low overcast layer due to a subsidence inversion caused by the subsiding air ahead of the high pressure ridge. The strengthening subsidence inversion (illustrated below) will most likely trap the low-level moisture and prevent skies from clearing.

In summary, skies are most likely to remain cloudy but clear breaks may develop over some locations.

Will skies be clear over southern Ontario Monday night?

Cloudy skies and fog are likely to continue over most or all regions, due to extensive moisture trapped at low levels by a strong and persistent subsidence inversion, and winds are too light to mix out and disperse the low-level cloud. Some breaks in the cloud could develop, and allow stars to appear over some locations, but generally overcast conditions are more likely with fog developing again overnight in many regions.

Will skies be clear over southern Ontario Saturday night?
It looks like the low-level cloud over southern Ontario will have a hard time dissipating during the afternoon and so there is a reasonable probability that low stratus will persist during the evening and cause partly cloudy skies in some regions and overcast skies in others, while skies could become clear in some areas. However, fog is likely to form overnight in most areas, and locations with clear skies will most likely be the first to become foggy.

Will skies be clear over southern Ontario Friday night?

Skies may become mostly clear by sunset, if the persistent low-level cloud over southern Ontario (trapped at low levels by a subsidence inversion) can dissipate. If the low-level cloud dissipates enough for skies to become mostly clear, then some high-level cloudiness may be visible, caused by a region of high-level moisture that is forecast to move southeastward over southern Ontario overnight (illustrated below for late evening).

Will skies be clear over southern Ontario Wednesday night?

Mostly cloudy skies are expected, but skies may appear partly clear during the early evening in some locations where gaps in the mid-level cloudiness allow partly clear sky to be seen occasionally.