London · Ontario · 2026–27 season
Snow Day Predictor LondonWill school be cancelled tomorrow in London?
Live overnight forecast for the City of London, Middlesex County, Strathroy, Woodstock, and the surrounding southwestern Ontario region. The predictor tunes to Thames Valley DSB and London District Catholic closure patterns, with Southwestern Ontario STS bus cancellation probability returned separately.
Multi-model forecast, five-factor closure engine, province-aware results. No sign-up, no tracking of your queries.
What makes London unique
London sits squarely in the Lake Huron snowbelt and receives some of the heaviest seasonal snowfall in southern Ontario. The combination of lake-effect bands off Lake Huron and the Goderich-to-London snow corridor produces routine winter weather events that close TVDSB and LDCSB.
Southwestern Ontario forecast
London snow day forecast, what to expect this winter
London is the largest city in southwestern Ontario and sits at a meteorological crossroads that produces some of the most reliable snow-day weather in the province. The city averages around 200 cm of snow per winter, almost double Toronto, and that total is driven mostly by lake-effect bands that form when cold northwesterly winds cross the open waters of Lake Huron. The corridor that runs roughly from Goderich southeast to London is one of the most prolific lake-effect snow producers in Canada, and it sets up multiple times each winter. When the band parks over the city, accumulation rates can exceed 5 cm per hour for hours at a time, the kind of overnight snowfall that closes schools rather than just cancelling buses.
School operations across London and Middlesex County are run primarily by the Thames Valley District School Board (TVDSB), the English public board covering London, Strathroy, Woodstock, and the rural townships, and the London District Catholic School Board (LDCSB), the corresponding Catholic system. Both boards rely on Southwestern Ontario Student Transportation Services (STS) to operate the school bus network. Unlike Toronto, where buildings rarely close, London regularly sees TVDSB and LDCSB close schools outright when a major lake-effect event hits, in addition to the more frequent bus-only cancellations that affect rural routes through Middlesex County.
For families across the London region, the morning weather call from Southwestern Ontario STS typically lands by 6:00 am and applies as a single decision across London, Middlesex County, Strathroy, and the Woodstock area. The predictor on this page returns the closure probability the night before, with a separate bus cancellation number for families on rural routes where the threshold is lower. Because lake-effect snow can be highly localized, we pull hourly forecast data at your exact coordinates rather than averaging across the city.
School boards
London school boards we model
The boards and transportation operators that make the morning closure call for London.
- Thames Valley District School Board (TVDSB)
English public board serving London, Middlesex County, Oxford County, and Elgin County. The largest board in southwestern Ontario and the primary closure decision-maker for the region.
- London District Catholic School Board (LDCSB)
English Catholic board for London and surrounding communities. Closure decisions typically align with TVDSB on major weather days; the boards coordinate through Southwestern Ontario STS.
- Conseil scolaire Viamonde
French-language public board with schools in London. Operates its own transportation and may make different closure calls than the English boards on borderline weather days.
- Conseil scolaire catholique Providence (CSC Providence)
French-language Catholic board covering southwestern Ontario including London. Smaller footprint with independent closure decisions on weather days.
Bus transportation
Southwestern Ontario Student Transportation Services (STS) coordinates bus operations for both Thames Valley DSB and London District Catholic. STS cancellation decisions are typically made by 6:00 am the morning of and apply as a single call across London, Middlesex County, Strathroy, and the Woodstock area. On heavy lake-effect days STS frequently cancels all routes while the boards separately decide whether to close buildings.
Local weather
London’s signature winter weather patterns
The phenomena that produce most London snow days.
- Lake Huron lake-effect snow
The defining London weather pattern. Cold northwesterly winds cross the open waters of Lake Huron and produce intense single-band snow squalls that line up along the Goderich-to-London corridor. Hourly snowfall rates of 5 to 10 cm are common, and a stationary band can drop 50 cm or more on the city while neighbouring areas stay clear. Most prolific in November, December, and early January before Lake Huron freezes.
- Colorado low storms with lake enhancement
When a Colorado low tracks across the lower Great Lakes and pulls northwesterly winds in behind the cold front, the synoptic snowfall is amplified by lake-induced enhancement off Lake Huron. These hybrid events produce the largest single-storm totals in London and are the pattern behind most multi-day school closures.
- Multi-lake exposure
When the wind aligns just right, London can receive contributions from both Lake Huron to the northwest and Lake Erie to the south at the same time. Dual-lake setups are uncommon but produce widespread heavy snow across the entire Thames Valley footprint rather than a narrow corridor.
- Thames River valley cold-air pool
The Thames River valley channels cold air through the heart of the city on clear calm nights, dropping temperatures in low-lying neighbourhoods several degrees below the airport reading. The cold pool changes precipitation type, sleet and freezing rain in the valley while higher ground sees plain snow, and complicates bus route assessments.
- Freezing rain on the southeast side
Warmer air aloft tracking up from Lake Erie reaches the southeast side of London first, producing freezing rain on the south and east edges of the city while the northwest stays in snow. The split has produced school closures driven by ice rather than snow accumulation.
History
Notable London snow days in recent winters
Storms and ice events that shaped how London school boards approach the morning call.
Lake Huron lake-effect siege
December 11-13, 2010A stationary lake-effect band parked over the Goderich-to-London corridor for nearly three days, dumping more than 100 cm of snow along the snowbelt. Thames Valley DSB closed schools across the region, Highway 402 was shut down with motorists stranded overnight, and the Canadian Forces were called in to assist with rescues. The event is still cited as the benchmark modern London snow emergency.
Multi-day lake-effect closures
December 2017A persistent northwesterly flow set up a Lake Huron band that sat over London for the better part of a week in mid-December. Daily snowfall ran 20 to 40 cm and Thames Valley DSB and London District Catholic closed schools on multiple consecutive days. Southwestern Ontario STS cancelled buses every morning of the event.
Southwestern Ontario ice storm
December 21, 2013The freezing rain event that crippled the Greater Toronto Area spread west into London with ice accretion heavy enough to bring down trees and power lines. LDCSB and TVDSB closed schools and tens of thousands of households across Middlesex County lost power into the Christmas holidays.
Polar vortex extreme cold
February 2019A polar vortex displacement drove wind chill values below minus 40 degrees Celsius across southwestern Ontario for several days. Thames Valley DSB and London District Catholic modified operations and Southwestern Ontario STS cancelled buses on the coldest mornings. The event is the modern benchmark for cold-driven closures in London.
Southern Ontario blizzard
January 14, 2022The same Colorado low that produced the GTA blizzard tracked across southwestern Ontario, dropping 30 to 40 cm of snow on London with sustained winds over 60 km/h. TVDSB and LDCSB closed all schools and Southwestern Ontario STS cancelled all routes. Highway 401 closed between London and Tilbury.
Lake Huron squall outbreak
January 17, 2024A sharp arctic outbreak crossed an unfrozen Lake Huron and produced a multi-day squall event with hourly snowfall rates above 7 cm under the heaviest bands. Thames Valley DSB closed schools and buses were cancelled across Middlesex County and the Strathroy area on consecutive mornings.
FAQ
London snow day frequently asked questions
The 7 questions London parents and teachers ask us most.
Will Thames Valley DSB close tomorrow?
Type your London postal code or "London, Ontario" into the predictor above. Unlike Toronto, Thames Valley District School Board (TVDSB) does close school buildings outright when a major lake-effect event or Colorado low is forecast, and it is one of the more closure-prone large boards in southern Ontario. The decision is typically announced by 6:00 am the morning of through the TVDSB website and social channels. Our predictor returns the closure probability the night before based on the overnight forecast.
How does the Lake Huron snowbelt affect London schools?
London sits at the southern end of the Goderich-to-London snowbelt corridor, the band of land that receives lake-effect snow off Lake Huron when northwesterly winds cross the still-open lake. Hourly snowfall rates of 5 to 10 cm are common under a stationary band, and the corridor regularly produces 50 cm or more in a single overnight event. That intensity, far heavier than synoptic snow elsewhere in southern Ontario, is the main reason TVDSB and London District Catholic close schools more often than boards farther east.
Will school be cancelled in Strathroy or Woodstock tomorrow?
Both Strathroy and Woodstock fall within Thames Valley DSB and Southwestern Ontario STS territory, so they share the same morning weather call as London itself. The single STS decision applies across London, Middlesex County, Strathroy-Caradoc, and the Woodstock area. On lake-effect days the snowfall can be heavier in Strathroy (closer to Lake Huron) than downtown London; on Colorado low events Woodstock to the east often sees the heavier totals. The predictor pulls forecast data at your specific coordinates.
Are LDCSB Catholic schools closing with TVDSB today?
London District Catholic School Board (LDCSB) and Thames Valley District School Board (TVDSB) make closure decisions independently but almost always align on weather days, because they share Southwestern Ontario STS for transportation. If STS cancels buses, both boards typically follow with the same closure decision. The official LDCSB call comes through the board website and social media by 6:00 am the morning of.
What causes London to get more snow than Toronto?
London receives roughly 200 cm of snow a year compared to Toronto’s 120 cm, and the difference is almost entirely lake-effect snow off Lake Huron. Toronto sits on the north shore of Lake Ontario, which produces lake-effect bands aimed east into Durham Region, not toward downtown Toronto. London, by contrast, sits directly downwind of Lake Huron’s long fetch when northwesterly winds blow, the optimal geometry for heavy single-band squalls. The result is more frequent and more intense snow days, and noticeably higher school closure rates than the Greater Toronto Area.
Will school buses be cancelled in London tomorrow?
For the official call, check the Southwestern Ontario Student Transportation Services portal (mybigyellowbus.ca) and the TVDSB and LDCSB websites. STS announces bus cancellations by 6:00 am the morning of, applicable to both English boards across London, Middlesex County, Strathroy, and the Woodstock area. Buses are cancelled more often than buildings close, particularly for the rural routes that wind through Middlesex County. Our predictor returns a separate bus cancellation probability the night before.
How does Middlesex County rural weather differ from city schools?
Rural Middlesex County schools and bus routes sit closer to the open snowbelt fetch off Lake Huron and lose plowing priority compared to the City of London. The result is that rural buses cancel for storms that leave city schools fully operational, especially on lake-effect days when the heaviest band sits over Strathroy-Caradoc, Lucan Biddulph, or Adelaide Metcalfe rather than central London. Southwestern Ontario STS makes a single regional call, so a heavy rural morning usually cancels buses for the entire system even if downtown London looks clear.
Near London
Nearby Ontario cities
Other Ontario cities our forecast covers — same regional profile, different local weather.
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