Partly clear skies are likely during early Monday evening, except for increasing high clouds that may or may not be visible, as jetstream-level moisture begins moving eastward across southern Ontario (illustrated below for early evening). Increasing cloudiness is expected as mid-level (and lower) moisture moves over southern Ontario later in the evening.

Will skies be clear over southern Ontario Saturday night?

Partly clear skies are likely as a result of a high pressure ridge building over the area, but partly cloudy skies are expected over southwestern regions as a result of jetstream-level moisture over southern Ontario, approximately west of GTA (illustrated below during early evening) and a strong jetstream which may have high-level clouds associated with it that may be easily visible in the bright moonlight. Also, mid-level moisture over southwestern regions near Lake Erie may cause mid-level cloudiness during the evening, and low-level cloudiness from Lake Huron flowing southward over southern Ontario may also cause some cloudiness.

Will skies be clear over southern Ontario Friday night?

Clearing skies are expected before sunrise over northern parts of southern Ontario as most of the cloudiness with Friday’s cold front moves southeastward overnight. High clouds may be visible in the bright moonlight due to jetstream-level moisture which will be over southern Ontario. Southwestern regions, approximately west of Lake Ontario, will most likely remain cloudy as mid-level moisture remains over that area until later Saturday (illustrated below for 4 am EST).

It looks like skies may appear to be partly clear during the evening, particularly with a full moon in the sky, except for high cloudiness which is expected to increase overnight (illustrated below) until mid-level cloudiness causes mostly cloudy skies by sunrise Thursday (ahead of Thursday’s low pressure trough).

Will skies be clear over southern Ontario Tuesday night?

Some medium or high-level clouds may be visible during the evening and then mostly clear skies are likely over most regions overnight. The illustrations below show the high-level moisture that may appear as mid-high level cloudiness during early evening and the mid-level moisture that may cause some cloudiness over southwestern regions later in the evening.

Will skies be clear over southern Ontario Sunday night?

Skies are likely to become mostly clear by sunset over most regions, except for more mid-level cloudiness west and and north of Lake Ontario during the early evening caused by a region of mid-level moisture (illustrated below during early evening) and then occasional patches of low-level cloudiness may appear over regions south and east of Lake Huron overnight, caused by a region of low-level moisture (illustrated below during late evening at 850 hPa level) as well as some lake-effect cloudiness from Lake Huron.

Will skies be clear over southern Ontario Friday night?

It looks like skies may remain partly or mostly clear over eastern parts of southern Ontario during early evening, but high-level moisture spreading eastward across southern Ontario (illustrated below) will most likely cause increasing high cloudiness to appear by mid evening. Further west, toward SW Ontario, skies will most likely be cloudy by sunset.

Will skies be clear over southern Ontario Thursday night?

Mostly clear skies are likely, except for some low-level cloudiness mainly during the first couple of hours after sunset, as afternoon cloudiness gradually dissipates under subsidence caused by a high pressure ridge extending northeastward over southern Ontario (illustrated below), and except for more low-level cloudiness east of Lake Huron, as a result of cool SW winds flowing across the warmer lake.

Some high cloudiness may appear over southern Ontario overnight, caused by high-level moisture which is forecast to move eastward over southern Ontario (illustrated below during the evening) and skies could remain mostly clear over some regions.

Will skies be clear over southern Ontario Monday night?

It looks like skies will remain clear until mid-level moisture ahead of a low pressure trough (moving northeastward toward southern Ontario) moves over southern Ontario beginning near Lake Erie during the evening and then over all of southern Ontario after midnight, illustrated below for late evening.

Will skies be clear over southern Ontario Sunday night?

Clear skies are forecast (and a high pressure ridge, subsidence, and dry air).

Will skies be clear over southern Ontario Saturday night?
Mostly cloudy skies are expected during the evening over most regions due to an upper-level trough moving eastward across southern Ontario during the evening, and a region of mid-level moisture over southern Ontario during the evening (illustrated below). Later, overnight, gradually clearing skies are expected over most regions as the trough and moisture move eastward, and subsidence ahead of a high pressure ridge causes moisture and clouds to subside.

Will skies be clear over southern Ontario Friday night?
Mostly cloudy skies are expected, due to a large area of low-level moisture (illustrated below) that is forecast to be over most regions of southern Ontario overnight, but occasional clear breaks are possible and may allow skies to appear partly or mostly clear from time to time over some locations.

Will skies be clear over southern Ontario Thursday night?

If skies appear clear during the early evening, increasing high cloudiness ought to cause skies to be cloudy by about mid-evening over most regions.

Will skies be clear over southern Ontario Wednesday night?

Clear skies are expected during the evening until low-level cloudiness (and fog) develops after midnight over most regions, except earlier over some southwestern regions, caused by a region of moisture forecast to move northeastward over southern Ontario overnight (illustrated below after midnight). High humidity and calm winds will allow fog to form in the locations with lower elevations earlier in the evening.

Tuesday night: clear skies!

Will skies be clear over southern Ontario Monday night?

It looks like skies will be mostly clear, except for some scattered mid-level clouds that may be visible for several hours during early evening over regions near and north of GTA, due to a region of mid-level moisture (illustrated below) moving eastward across central Ontario during Monday afternoon.

Will skies be clear over southern Ontario Sunday night?

Skies are likely to be clear by sunset over most regions, except for regions near and north of GTA, where low-level moisture (illustrated below at 850 hPa level) will most likely cause some low-level clouds to be visible for several hours following sunset.
Later, mid to high-level clouds may appear over most regions of southern Ontario before sunrise as a result of high-level moisture (illustrated below at 500 hPa level) which is forecast to move eastward over southern Ontario. By then (early morning), fog is likely to develop over most regions of southern Ontario as a result of the humid air over southern Ontario during Sunday afternoon and night and diminishing winds by midnight.