London Ontario Snow Day Predictor
A free London Snow Day Calculator. Enter your postal code, check the live weather, and see today's closure risk in seconds.
School Closure Analysis
London Snow Day Calculator
Trying to figure out if school gets cancelled tomorrow in London, Ontario? This free London Snow Day Calculator gives you a fast answer. Type in your postal code, and it checks the live weather to work out how likely a closure is.
It looks at three things: how much snow is falling, how strong the wind is, and how cold it actually feels. Those three get combined into one number called a closure risk score. It's just a percentage. The higher it is, the more likely buses or schools get cancelled.
This tool won't replace the real call from TVDSB or LDCSB. Those decisions get made early in the morning, usually before 6 a.m. What this tool gives you is a heads-up the night before, so you're not caught off guard.
Tracking snow in another Ontario city too? Our Hamilton Snow Day Predictor works the same way.
How the London Ontario Snow Day Predictor Works
The tool runs the same steps every single time:
- Enter your London postal code and pick your school type.
- Click Get Current Weather. The tool finds your location and pulls live weather from Environment Canada.
- Click Predict London Ontario School Closure Risk. This is where it does the math.
- Temperature, wind speed, and the current forecast (snow, heavy snow, or a squall) each get a weight based on how much they usually mess with roads and buses.
- Add it all up and you get your closure risk score, snowfall estimate, travel risk, and roof snow weight.
Use it next to Environment Canada's forecast and your school board's own alerts, not instead of them.
Will Schools Close Today in London, Ontario?
TVDSB and LDCSB look at more than just how much snow fell overnight. Road conditions, sidewalk ice, and how far buses have to travel in rural parts of the board all play a part.
- 1-5 cm: Usually no real impact.
- 5-10 cm: Bus delays get more likely, especially on rural routes.
- 10-20 cm: Bus cancellations become common.
- 20 cm or more: Full school closures start to become likely.
Quick thing worth knowing: a bus cancellation is not the same as a school closure. If buses are cancelled, the building is usually still open, and kids who can get there another way are still expected to show up. A school closure means the whole building shuts down for everyone. TVDSB and LDCSB will cancel buses far more often than they'll close a school outright, so always check which one was actually announced.
How Much Snow Did London Ontario Get? (Snowfall Averages)
Most snow days in London are small. Around 13 days a year bring at least 5 cm, and bigger storms, the kind dropping 10 cm or more, happen about 4 times a year on average.
Truly major blizzards, ones dumping 25 cm or more in a single day, are rare here. They only happen about once a decade. Snow usually starts building on the ground in late December, and London holds a centimetre or more of snow on the ground for about 84 days a year, with a typical mid-winter depth of around 11 cm.
So if someone's asking how much snow did London Ontario get this week, most winters the honest answer is small amounts spread across many days, with the occasional bigger storm mixed in.
Biggest Snowstorm in London, Ontario History
The one storm every long-time Londoner still talks about is the Great Blizzard of 1978. Between January 25 and 27, 1978, this storm dumped 41 cm of snow on London, with wind gusts hitting 128 km/h. It's still considered one of the worst winter storms to ever hit Southwestern Ontario.
That same storm system, sometimes called the "Cleveland Superbomb," also caused major damage across Ohio and the Great Lakes, killing over 50 people in Ohio alone. In Canada, it brought blizzard conditions across the whole southwestern part of the province, with London taking one of the hardest hits.
More recently, February 2025 brought a stretch of back-to-back storms across Southern Ontario, with the Lake Huron shoreline near London seeing 20 to 30 cm from a single system. It was a reminder that London, sitting close to the Lake Huron snowbelt, can still get buried even in years without a headline-grabbing blizzard.
Is There Snowfall in London Right Now? Why It Depends on Which Street You're On
Here's something that confuses a lot of people new to the area: it can be snowing hard on one side of London and completely dry ten minutes away. That's not a glitch in a weather app. It's how lake-effect snow squalls actually work.
A snow squall is a short, sudden burst of heavy snow that drops visibility fast, sometimes down to almost nothing, then clears up within an hour or two. London sits close enough to Lake Huron that cold air moving over the warmer lake water picks up moisture and dumps it as snow once it reaches land. These squalls travel in narrow bands, so one neighbourhood gets buried while another stays clear.
This is exactly why a single citywide snow forecast for London doesn't tell the whole story. If you're checking the London snow forecast and it says "flurries," that can still mean a sudden squall rolls through your specific area later that day. Checking conditions by your own postal code, like the calculator above does, gives you a more honest picture than a general city forecast.
Snow Squall Warning vs. Winter Storm Warning: What's the Difference?
Environment Canada uses different alerts for different kinds of snow, and mixing them up leads to a lot of confusion.
A snow squall warning means a short, intense band of heavy snow is expected, often with very low visibility for an hour or two. These come on fast and can catch drivers off guard on the highway, even if the rest of the day looks calm.
A winter storm warning means a longer, broader system is moving through, usually bringing a mix of steady snow, wind, and sometimes ice over many hours across a wider area.
The short version: a squall warning is about a sudden, sharp burst in a small area. A storm warning is about a longer event covering a much bigger stretch of the region. Both can shut down travel, but they call for different plans. A squall might mean waiting an hour before you drive. A storm warning might mean rethinking the whole day.
Snow Removal London Ontario: Residential and Commercial
Once the snow's down, someone has to move it. Snow removal London Ontario companies get busy fast once a storm passes 10 cm, so booking before the forecast turns usually gets you a quicker response than calling once the snow's already falling.
Residential Snow Removal London Ontario
Residential snow removal London Ontario services usually cover driveways, walkways, and front steps. Most companies offer either a per-storm rate or a flat seasonal contract. Getting your driveway cleared early, before overnight temperatures drop, stops loose snow from turning into a sheet of ice by morning.
Commercial Snow Removal London Ontario
Commercial snow removal London Ontario contracts typically cover parking lots, loading zones, and building entrances. Most businesses schedule their lot cleared before opening hours, both for convenience and to cut down on slip-and-fall risk once customers and staff start arriving.
What Happens During a London Snow Emergency?
When a bigger storm is on the way, the City of London puts its winter maintenance plan into action to keep main roads open.
- Priority routes and main roads get plowed first.
- Parking restrictions may kick in on designated winter routes.
- Plows work through arterial roads before side streets and residential areas.
- London Transit Commission (LTC) buses may run delayed or altered routes.
- Schools may adjust hours or cancel buses depending on how bad conditions get.
Always check the city's official alerts during a bigger storm, especially if a snow squall warning is layered on top of an already messy commute.
Roof Snow Weight in London, Ontario
Wet, heavy snow adds real weight to a roof, and freeze-thaw cycles (where snow melts a little during the day and refreezes overnight into ice) make this more of an issue in London than in drier, colder places.
- Dry, powdery snow is light and doesn't add much weight.
- Wet, heavy snow weighs a lot more for the same depth.
- Ice from freeze-thaw cycles adds more stress than fresh snow alone.
- Flat or low-slope roofs collect deeper buildup than steep, pitched ones.
Treat the roof weight number from the calculator above as a starting point. If it looks high after a run of storms, get a roofer to take a look in person.
Check Weather By London Ontario Area
Because of how squalls and lake-effect bands work, snow totals can shift a lot from one part of London to another. Checking your own postal code beats guessing from a single citywide number.
- N6A — Downtown London
- N6G — North London
- N6E — South London
- N5Y — East London
- N6K — West London / Byron
- N5X — Far north / near Masonville
The calculator pulls current conditions for whichever postal code you enter, using Environment Canada data.
How London Parents Handle Snow Days
Every storm, London families run through the same routine: check TVDSB or LDCSB's website, check LTC for bus delays, and line up a backup plan for childcare in case things change fast.
- Check your school board's website or app first thing in the morning.
- Watch LTC for delayed or cancelled routes.
- Give yourself extra time driving. Black ice under fresh snow is the real hazard, not the snow itself.
- Have a backup childcare plan ready, since closures don't always come with much notice.
- Remember: a bus cancellation is not the same as school being closed.
Explore More Winter Weather Tools
Keeping an eye on snow somewhere else too? Check our other city snow day and snowfall tools.
Official London, Ontario Winter Weather Resources
Before making a travel or school decision during a bigger storm, check these directly.
- Environment Canada
- City of London
- Thames Valley District School Board
- London District Catholic School Board
These cover official weather alerts, road conditions, and school board announcements for London, Ontario.
Frequently Asked Questions
How accurate is the London Ontario Snow Day Predictor?
It's an estimate built from live temperature, wind, and forecast data, not an official decision. TVDSB and LDCSB make the real call, usually announced early in the morning.
How much snow usually closes schools in London, Ontario?
Bus cancellations tend to start once snowfall passes 10 cm, or sooner on rural routes with a bad forecast. Full school closures usually need 20 cm or more, or genuinely unsafe road conditions.
Is there snowfall in London right now?
Run the calculator above with your postal code for a live answer. Because of squalls, it can be snowing in one part of the city and clear in another at the same time, so a citywide answer alone won't always be accurate for your street.
What was the biggest snowstorm in London Ontario's history?
The Great Blizzard of 1978 still holds that title. It dropped 41 cm on the city between January 25 and 27, 1978, with wind gusts up to 128 km/h.
How much snow did London Ontario get this year?
Use the calculator above for a live number based on your postal code, or check Environment Canada's London station data for confirmed seasonal totals.
Why does London get sudden snow squalls?
London sits close enough to Lake Huron that cold air crossing the warmer lake picks up moisture and dumps it as snow in narrow bands once it reaches land. That's why squalls can hit one neighbourhood hard while leaving another dry.
When should I book snow removal in London, Ontario?
Before the storm hits, ideally. Both residential and commercial snow removal London Ontario providers fill up fast once snow is already on the ground.
Does this tool use real Environment Canada data?
Yes. It pulls live weather from Environment Canada for the postal code you enter and uses that to estimate closure risk.