By the time the storm finishes Wednesday, large swaths of southern Ontario could have snowfall accumulations of between 20 and 30 centimetres. (CBC)

Almost all schoolchildren in the Toronto area have a snow day as school boards across the region called off classes due to a major storm hitting southwestern Ontario.

An estimated 15 to 25 centimetres of snow are expected to accumulate in parts of the Greater Toronto Area by Wednesday afternoon. CBC.ca has compiled the following list of key information, links and numbers where readers can get updates about services that may be affected by the storm.

The following information covers travel and school closures.

Schools (Toronto)

All classes in the Toronto District School Board have been cancelled.

All Toronto Catholic School Board classes have been cancelled.

The Glendon and Keele campuses of York University have been closed. Osgoode Hall in downtown Toronto has also been closed.

The Mississauga campus at the University of Toronto has been shut down. Classes have been cancelled at the university's Scarborough campus, although offices remain open.

Centennial College is closing all its campuses, as well as daytime and evening classes for Wednesday.

Humber College says all campuses and services will be closed on Wednesday, including daytime and evening classes, events and campus child-care centres.

All Sheridan College campuses will be closed on Wednesday.

There are also a number of closures at private schools around the city.

Schools (outside Toronto)

All Peel Region District School Board schools have been closed.

All Dufferin-Peel Catholic District Catholic School Board schools have also been closed.

There is no bus service in York Region (Aurora, King, Newmarket, East Gwillimbury, Georgina, Markham/Richmond Hill, Vaughan, Whitchurch-Stouffville), although schools are open. York Region District School Board shares bus service with the York Catholic District School Board. Check this site for York Region District School Board information and this site for information about the York Catholic District School Board.

All Durham Region Catholic and Durham Public District schools are open. However, there is no bus service in the district. People can find more inormation about bus service here. Durham covers Pickering, Ajax, Whitby, Oshawa, Clarington, Uxbridge, Brock, and Scugog.

All Halton District School Board and Halton Catholic District School Board schools are closed. Halton covers Burlington, Oakville, Milton and Halton Hills. The closures also affect all Halton French public schools and Catholic schools.

All schools in Hamilton-Wentworth are closed Wednesday. Both Catholic and public schools share bus service in this region.

McMaster University in Hamilton will be closed all day Wednesday. The closure includes all classes, events, non-essential operations and meetings.

Mohawk College has been closed for the day. The closure affects three campuses — Fennell campus in Stoney Creek, the Mohawk Laurier Centre in Brantford and the Mohawk-McMaster Institute for Applied Health Sciences in Brantford.

Flights

More than 300 flights at Toronto's Pearson Airport were cancelled between Tuesday night at 8 p.m. and midnight on Thursday. The Greater Toronto Airport Authority has provided live flight information here but passengers should also check with their airline.

Air Canada has a daily outlook that provides information on flights here.

All Porter Airlines flights out of Billy Bishop Toronto City Airport have been cancelled until noon. For more information call 1-888- 619-8622 or visit Porter's website.

Trains

Via Rail expects a sharp rise in demand for seats in the Ontario-Quebec corridor on Tuesday and Wednesday as drivers avoid snowy highways. A statement on their site posted Tuesday said they are prepared to handle the extra volume. Passengers, however, are asked to arrive earlier than normal as long lines are expected. For more information call 1-888-VIA-RAIL, or visit their website.

There have been no significant disruptions on the Toronto Transit Commission. A spokeswoman said that traffic on Wednesday has been lighter than usual. TTC Twitter feed @ttcnotices will have regular updates about any significant service interruptions. For updates about service interruptions via email, sign up for TTC service e-alerts here.

GO Transit Service updates are posted here. GO also has a GO in the Snow page, with information about using GO during severe winter weather. Also, GO train riders can sign up for e-alerts here to get service information sent to their mobile devices.

Driving

The Ontario Ministry of Transportation advises drivers to check weather and road reports before they leave and avoid unnecessary travel. Their website has this interactive map listing road conditions. There is also a provincial call centre with recorded road information about provincially maintained highways. The number is 1-800-268-4686. In the Greater Toronto Area: 416-235-4686.

With files from The Canadian Press