London Snow Day Predictor 2026: Live Chances

London, Ontario · Snow Day Predictor Canada

London might be the most interesting snow-day city in Ontario. It’s far enough south to dodge some storms — and squarely in the path of Lake Huron’s snow squalls, which don’t care about forecasts for the city as a whole. The result: buses cancelled in the counties while the city runs normally, 50-centimetre overnight dumps, and some of the most debated closure calls in the province. Here’s the live picture plus how London actually decides.

How to Read Your London Score

Each percentage is our estimate of the chance that London-area school buses get cancelled or schools close tomorrow, based only on the weather forecast:

• Under 20%: Normal winter day. Everything runs.
• 20–49%: Worth watching — especially the squall forecast. Check mybigyellowbus.ca before bed.
• 50–79%: Good chance of cancellations, at least outside the city. Have a backup plan.
• 80% and up: Start planning like it's happening.

The score comes from four things: forecast snowfall, peak wind gusts, the overnight low, and the overall weather code. It refreshes every time you load the page.

One London-specific note: the score covers the whole London area, but cancellations often split — counties out, city running. Read the section below on the London split before trusting a single number.

Will London Schools Close Tomorrow?

The official word lands at 6:30 AM on mybigyellowbus.ca — that's the site run by Southwestern Ontario Student Transportation Services, and it's where every inclement-weather cancellation is posted by half past six on the morning of the event. The same notice goes to X, Instagram, Facebook, email subscribers, and the BusPlanner Delays app simultaneously.

What to know about London announcements:

• 6:30 AM is the posting time — later than Hamilton's 6:00, and it matters on marginal mornings.
• The TVDSB website and social channels carry school-closure decisions (as opposed to bus cancellations).
• If weather hits during the school day, the call typically comes by 11:30 AM.
• Fog cancellations are morning-only — afternoon service runs. Every other weather cancellation is the full day.

The London Split: Why the Counties Cancel When the City Doesn't

This is London's signature snow-day pattern, and it confuses newcomers every winter: buses get cancelled across Middlesex, Oxford, and Elgin counties — the "Red Zone" — while City of London routes run normally.

Why? The counties are exposed to open-road lake-effect squalls and drifting on rural routes, while the city itself is somewhat sheltered and gets cleared faster. The same storm can be a normal school day at a city school and a day off twenty minutes away. In nearly every London snow event, the headlines read the same way: "buses cancelled outside London, city routes running."

So when you check the score above, remember: a 60% day might mean your county-bus rider is home while your city-walker neighbour heads to class. Check mybigyellowbus.ca for your specific zone — that's the only source that splits it properly.

How London's Boards Actually Decide

Four boards serve the London area: the Thames Valley District School Board (TVDSB), the London District Catholic School Board (LDCSB), Conseil scolaire catholique Providence, and Conseil scolaire Viamonde. Student transportation runs through Southwestern Ontario Student Transportation Services (STS).

Here's the twist most people don't know: the decision to cancel a bus run rests with the school bus company itself, not with STS. The operators know their routes and vehicles; when they judge it unsafe, the run is cancelled and STS posts it.

And the TVDSB's standing rule: in most cases, when buses are cancelled, schools remain open. Walkers and driven students have a normal day. (The board briefly flipped this during the pandemic — closures on bus-cancellation days — then reversed it: bus cancellations no longer mean school closures.) If a full closure happens, the board says virtual learning continues through its usual platforms.

Lake-Effect Squalls: London's Snow-Day Engine

London sits in one of the most heavily populated snowbelt corridors in Ontario's southwest, squarely downwind of Lake Huron. When cold Arctic air crosses the relatively warm lake, it builds narrow, violent snow squalls that can drop snow at 5–10 cm per hour. Environment Canada's warning for these events is blunt: you can be driving in clear conditions and have visibility collapse with almost no warning.

The receipts: a December 2024 lake-effect blast buried London under roughly 57 cm; one overnight squall dropped 14–16 cm with another 50 cm in the forecast. On January 8, 2025, up to 25 cm cancelled every London, Middlesex, and Red Zone bus as of 6:30 AM — and Western University cancelled morning classes.

It's not always snow, either. In January 2026, every LDCSB bus was cancelled and all LDCSB schools and offices closed on a −22°C wind chill — no blizzard required. Extreme cold alone can end the debate in this part of Ontario.

For the province-wide view — live chances in 8 cities and how every region decides — see our Ontario snow day guide. And for the snowbelt's other capital, our Barrie predictor tracks Georgian Bay's squalls daily.

What Counts Toward a London Snow Day?

Our predictor scores the same four factors behind real cancellation decisions:

• Snowfall amount: The biggest driver — but in London, rate matters as much as total. A 15 cm overnight dump and a 15 cm squall morning are very different days.
• Wind gusts: Squalls plus wind is the classic London cancellation recipe — whiteouts on county roads with modest totals in the city.
• Overnight low: Deep cold hits bus fleets mechanically and makes rural stops unsafe; −20s wind chills have closed schools outright.
• Weather code: Snow-squall warnings (not just snowfall warnings) are London's characteristic trigger — and freezing rain can do the job with barely any snow at all.