St. Thomas Snow Day Predictor – Thames Valley DSB and London District Catholic
Will Tomorrow Be a Snow Day?
Canada's most accurate snow day predictor
St. Thomas sits just south of London in Southwestern Ontario, close to the north shore of Lake Erie. The city shares the Thames Valley District School Board (TVDSB) with London and averages approximately 160-200 cm of snow per year, influenced by both Lake Huron and Lake Erie lake-effect snow. Its position in Elgin County means the TVDSB’s rural bus routes across flat, exposed farmland are a central factor in closure decisions.
Will St. Thomas schools be closed tomorrow? Enter your city in the predictor above for tonight’s closure probability, updated hourly from Environment Canada data. Always confirm with your school board’s official channels before making plans.
St. Thomas School Boards – Who Decides Closures
- Thames Valley District School Board (TVDSB) – St. Thomas, London, Woodstock, Strathroy, and rural Elgin, Middlesex, Oxford counties. tvdsb.ca | Announces: by 6:00 AM | Radio: AM 1290 CJBK, 1410 CFTE | Twitter/X: @TVDSBschools
- London District Catholic School Board (LDCSB) – Catholic board for London and St. Thomas area. ldcsb.ca | Announces: by 6:00 AM | Twitter/X: @LondonCatholic
- Conseil scolaire Viamonde / MonAvenir – French boards serving the region.
St. Thomas Snow Day Triggers – What Closes Schools Here
St. Thomas closures are driven by:
- Lake Erie and Lake Huron lake-effect: St. Thomas sits between two Great Lakes, catching lake-effect snow bands from both Lake Huron (northwest winds) and Lake Erie (southwest winds).
- Rural Elgin County drifting: The flat, open farmland of Elgin County produces significant blowing and drifting snow that closes rural bus routes even when St. Thomas streets are clear.
- Regional storms: Major systems affecting London and Southwestern Ontario deliver significant snowfall to St. Thomas.
How Often Do St. Thomas Schools Close?
The Thames Valley DSB averages approximately 4–7 full closure days per year, with rural bus cancellations across Elgin and Middlesex counties more frequent. St. Thomas typically follows London’s board-wide decisions. January and February are peak months.
See Also – Nearby Predictors and Guides
Explore the Ontario Snow Day Predictor for all school boards in the province, or check nearby cities:
Related guides:
Frequently Asked Questions – St. Thomas Snow Days
Which school board and bus zone does the St. Thomas predictor track?
The predictor tracks data for the Thames Valley District School Board (TVDSB) and the London District Catholic School Board (LDCSB). For student transportation, St. Thomas is located within the Elgin County / South Zone of the Southwestern Ontario Student Transportation Services (STS).
Why does the predictor spike for St. Thomas when London roads are completely clear?
St. Thomas sits closer to Lake Erie, putting it directly in the path of intense lake-effect snow squalls that blow off the water. The predictor calculates risk based on regional conditions, meaning heavy snow bands can shut down buses in St. Thomas and Elgin County while neighbouring London sees clear skies.
How much snow triggers a high cancellation percentage on the St. Thomas predictor?
A standard snowfall rarely triggers a high percentage because local crews are highly experienced. The predictor’s algorithm spikes when a weather warning forecasts 10 to 15 cm of rapid morning accumulation, or when high winds create severe drifting snow and zero-visibility on rural county roads.
If the St. Thomas predictor hits 100% and buses are cancelled, are schools closed?
No, schools typically remain open for staff and students who can safely walk or arrange their own rides. The predictor helps parents anticipate “inclement weather days” where regular curriculum lessons and tests are officially paused, and no new graded work is introduced.
What time is the St. Thomas snow day predictor most accurate?
The most accurate time to check is between 5:00 AM and 5:30 AM on the morning of the storm. While a check at 9:00 PM the night before gives a good baseline estimate, overnight shifts in lake-effect snow squalls require final morning radar updates right before the official STS announcement at 6:30 AM.