The first frost and snowfall of the year will arrive over the northern Plains before the middle of the week.
"A major cold front will push southward through the Prairies Monday with a strong, Arctic high pressure system building in behind it," said AccuWeather Canada Weather Expert Brett Anderson.
The air behind this front will be cold enough for several inches of snow to fall over the Canadian Rockies and even in cities such as Calgary and Edmonton on Monday afternoon into Tuesday evening.
Snow is then forecast to make an appearance across Montana and into North Dakota on Tuesday night, although little is expected in terms of snow accumulation.
"The chilliest air since last spring will push southward from Canada and across the northern and central Plains, Midwest and the eastern slopes of the Rockies, prior to the middle of September," said AccuWeather Senior Meteorologist Alex Sosnowski.
This chilly air mass will continue to expand south and east throughout the rest of the week, but the coldest air will remain locked up over the Canadian Prairies and northern Plains.
Frost will be a major concern for those with outdoor plants that are sensitive to freezing temperatures such as flowers and garden plants. This includes plants such as tomatoes, squash, cucumbers and watermelons.
Frost may form several nights in a row across the northern Plains with frost also possible over parts the Upper Midwest during the second half of the week.
Covering your plants early in the night is one way to try and prevent frost from damaging your plants.
"On a broad-term agricultural standpoint, crops such as corn and soybeans are maturing about a week behind average, but with such a bumper crop anticipated, no significant impact is expected by the light spotty frost unless temperatures dip significantly lower than currently forecast," said Sosnowski.
Looking ahead to the upcoming weekend, the core of the chilly air mass will shift over the Great Lakes and away from the Plains.
However, those across the Great Lakes should not have to worry about temperatures dipping below freezing this weekend as the air mass responsible for the chilly weather slowly warms up throughout the latter part of the week.
Temperatures are still expected to run well below normal in cities such as Chicago and Detroit through the weekend.
Meanwhile, temperatures across the northern Plains will slowly rise, but remain 5 to 10 degrees below normal.