"All crews and hired equipment available have been working overnight and will continue until all routes and pedestrian facilities are complete," reads an update provided to city council.
The city said the amount, accumulation rate and heavy moisture content of the snow means crews likely won't be done with the major roads until late afternoon or early evening.
The city opened its emergency operations centre Tuesday morning. It is calling in extra contractors to help deal with the snow.
Snow route parking ban issued
A snow route parking ban has been issued, coming into effect Wednesday at 10 a.m. MT
The city will provide an update at 12:30 p.m MT today.
A record-breaking 15 to 25 centimetres fell in Calgary overnight, CBC meteorologist Christy Climenhaga told the Calgary Eyeopener Tuesday morning. The previous record for Oct. 2 was set in 1954 with only about five centimetres.
"But the all-time extreme record for one day in October is about 30 centimetres in 1914, so you guys are on your way to breaking that," she said.
The snowfall came fast and heavy, which made roads and highways slick for morning commuters.

Not everyone was bothered by the snow. The pandas at the Calgary Zoo seemed to enjoy it, but of course they didn't have to commute today.
Calgary Transit reported Tuesday morning buses that travel on hills were having trouble navigating the slippery roads, so commuters with stops in the middle of hills were asked to wait at either the top or bottom.
Buses on Routes 1, 2, 3, 4, 5, 6, 53, 72, 73, 93, 94, 305 and 777 are on snow detour, and both the Red and Blue lines of the LRT were running several minutes behind schedule.
According to Climenhaga, the cold and snowy weather system is the result of a steady flow of moisture coming over the Rocky Mountains from a low over the Pacific Ocean.
"What that's doing is it's colliding with an extremely cold air mass ... that has been set up over the Prairies for weeks, really ... but you're seeing a steady, steady line of moisture hitting that cold, cold air."

Two buses blocked the eastbound lanes of Memorial shortly before 7 a.m.
According to the agency, general snowfall amounts of 15 to 30 centimetres are expected, but up to 45 centimetres could fall in the mountains.

A man clears snow from a section of sidewalk along 14th Street S.W. early Tuesday morning.
Snowfall warnings are currently in effect for:
Airdrie - Cochrane - Olds - Sundre.
Banff National Park.
Cardston - Fort Macleod - Magrath.
Brooks - Strathmore - Vulcan.
City of Calgary.
Crowsnest Pass - Pincher Creek - Waterton Lakes National Park.
Jasper National Park.
Kananaskis - Canmore.
Lethbridge - Taber - Milk River.
Nordegg - Forestry Trunk Road Highway 734.
Okotoks - High River - Claresholm.
Comment:
Update: CBC further reports: