What's a Colorado Low and Why Does It Matter for Snow?

4 min read · Thames Valley Snow, London, Ontario

A Colorado low is a type of storm system that forms in the lee of the Rocky Mountains near Colorado and tracks across the continent toward the Great Lakes region, and it is responsible for some of the biggest snowfall totals southern Ontario sees each winter.

What makes a Colorado low different from a typical passing snow shower is scale and moisture. These systems pull in Gulf of Mexico moisture as they travel northeast, then dump it as heavy, prolonged snowfall once they interact with the cold air already sitting over Ontario. The result is often a slow-moving storm that can drop 15 to 30 centimetres or more over 12 to 24 hours, sometimes longer.

Because Colorado lows track a specific, somewhat predictable path, meteorologists can usually spot them several days out, which gives more advance warning than a fast-forming lake-effect band. That lead time matters for snow removal planning, since crews can schedule extra equipment and staff ahead of a confirmed Colorado low rather than reacting last minute.

The storm's exact track still shifts right up until it arrives, and a shift of even 50 to 100 kilometres can mean the difference between a moderate snowfall and a major event for London specifically. That is why forecasts for these systems often get updated multiple times as the storm approaches.

How to Prepare When a Colorado Low Is Forecast

Because these storms are usually spotted days ahead, you have time to get ready:

• Move vehicles so the driveway can be cleared in one pass.
• Make sure driveway edges are marked so they can be found under deep snow.
• Stock ice melt for steps, and plan for slower travel the day the storm peaks.
• Check that your snow removal plan is active before the storm, not during it.

Heavy, Wet Snow Takes More Work

Colorado lows often bring heavier, wetter snow than the light, fluffy snow from cold arctic air. Wet snow is harder to shovel and harder on snowblowers, and it can raise the risk of strain injuries for anyone clearing by hand. For many homeowners, a big Colorado low is the storm that makes a professional plan worth it.

How Seasonal Service Handles Big Storms

On a Thames Valley Snow seasonal plan, service starts once 5 cm has fallen, so a long Colorado low storm can mean more than one visit as the snow keeps coming. You do not need to call; your property is on the route automatically. Every visit is recorded with timestamped photos, and the seasonal price does not change with the number of storms. Plans start at $650, or $70 for a single visit.

Colorado Lows Compared With Lake-Effect Snow

London also gets lake-effect snow, which forms when cold air crosses the open water of Lake Huron. Lake-effect bands can be intense but are often narrow, so one neighbourhood may get heavy snow while another stays nearly clear. A Colorado low is different: it is a large system that usually covers the whole region, so most of the city gets snow at the same time. That is why these storms tend to be the ones people remember, and why they put the most pressure on snow removal routes across London.

Frequently Asked Questions

How much snow can a Colorado low bring to London?

A strong Colorado low can bring 15 to 30 cm or more over 12 to 24 hours, though the exact total depends on the track.

Will the ice after the storm be handled too?

If you add seasonal salting ($175), it covers freezing rain and refreeze visits, which are common when temperatures swing after a big storm.

Want snow removal that starts without a phone call? Request a free quote or call or text (548) 888-8702. You can also read about residential snow removal or commercial snow removal.

What's included… and what's extra

A Thames Valley Snow seasonal residential plan starts from $650 for a standard driveway. It covers clearing the driveway every time snowfall reaches the trigger depth in your agreement, plus the windrow the city plow leaves at the end of the driveway. Larger driveways are priced on our snow removal prices page.

Popular add-ons, priced per season: walkway and steps $150–175, salting $175, priority service $125, pet-safe salt $120, driveway extension $95 and city sidewalk clearing $90. Add only what your property needs; everything is listed on the quote so there are no surprises. Get your fixed price or call or text (548) 888-8702.