How Cold Is Too Cold to Clean Windows Outside? A Late-Fall Guide for Anjou Homeowners

Exterior windows can be cleaned with water as long as the glass stays above freezing until it dries. In practice that means mild days with temperatures comfortably above zero, no overnight frost still clinging to the glass, and no freezing rain in the forecast. In Anjou and the rest of Greater Montréal, those days usually run out somewhere in November, so late October is the time to book the last outside clean of the year.

Anjou is mostly post-war bungalows, split-levels, semi-detached houses and duplexes, with a few low-rise condo buildings near the main roads. Almost all of it sits within easy reach of a water-fed pole, which makes it a good place to talk about how cold weather actually affects the work.

What happens when you wash glass in the cold

Window cleaning outside is a wet job. On a warm day, water runs off the glass and whatever is left evaporates in minutes. As it gets colder, three things change.

• Water dries slower. Cool air and weak late-fall sun mean the glass stays wet longer. That's when drips settle on frames and sills and leave marks behind.
• Glass can be colder than the air. After a clear night, windows on the shaded side of a house can sit below freezing well into the morning, even when the thermometer reads a few degrees above zero. Water hitting that glass can turn into a thin film of ice instead of running off.
• Frames, sills and caulking get stiff. Vinyl and rubber gaskets are less forgiving in the cold. Water that freezes in a gap or in a track can expand and make sliding windows hard to open.

None of this is dangerous to the glass on a mild fall day. It's the combination of cold glass, slow drying and frost that turns a clean into a streaky or icy one.

The temperatures that actually matter

There's no single magic number, and anyone giving you one is simplifying. What matters is the glass, not the forecast high. A few rules of thumb hold up well around Montréal:

• Days that stay several degrees above zero through the afternoon are generally fine for exterior work.
• Mornings after a frost are the tricky part. South and west facing windows warm up fast once the sun hits them. North facing windows and glass under deep eaves or porches can stay cold for hours.
• Rain or wet snow right after a clean undoes a lot of the result, so a dry stretch of a day or two is worth waiting for.
• Wind dries glass faster, which helps, but strong gusts make working with a long pole harder and blow spray onto siding.

If you're doing your own windows with a bucket and squeegee, the same logic applies. Soapy water on cold glass leaves more residue, and a squeegee drags rather than glides once the film starts to stiffen.

Why the pole method has its own season

Altara cleans exterior glass with pure deionized water through a water-fed pole. The water has had its minerals removed, so it dries without spots and doesn't need to be wiped off. That works very well from spring through fall. It relies on the water running off and evaporating cleanly, though, and that stops being reliable once the glass is cold enough to freeze it.

That's the main reason exterior work is seasonal, running roughly from March to November. Interior glass is a different story: it's warm and dry inside, so interior cleaning runs all year.

A late-fall checklist before the last exterior clean

If you want one more outside clean before winter, a little preparation helps the crew and gets you more out of the visit.

• Count your windows. The flat rate is set by window count, and you pick your tier on the pricing page. Count every pane you want done, including basement windows and patio doors.
• Clear the ground. Move patio furniture, planters and garden hoses away from the walls so the crew can walk the perimeter.
• Decide on screens. Screens are rinsed in place as part of the exterior clean. If you'd rather have them taken out and washed properly before storing them for winter, that's an optional paid add-on.
• Look at the tracks. Fall leaves, seeds and grit end up in sliding window and patio door tracks. Track cleaning is an optional paid add-on, and it's worth doing before water in the track has a chance to freeze.
• Note any torn screens or cloudy units. Altara doesn't repair screens or replace sealed glass, but the crew will point out tears and fogged units so you can get them fixed before spring.

What the exterior flat rate covers

The flat rate covers the outside of your windows: glass, frames and sills, cleaned with pure water on the pole, with screens rinsed in place. Interior glass, screen removal and washing, and track cleaning are optional paid add-ons. Skylights, solariums, heavy mineral stains and post-construction cleanup are quoted separately.

The pole reaches up to three storeys from the ground, which covers nearly every house in Anjou. Taller buildings or homes with awkward access, like a steep slope or a fenced yard with no way through, get a site visit first. There's more about the area on the Anjou service page.

If you notice a streak after the visit, report it within 24 hours and the crew comes back to fix it at no charge.

Planning for next year

If you already know you'll want clean windows every season, a recurring plan saves some work. Quarterly service comes with a 10 percent discount, bi-monthly with 15 percent and monthly with 20 percent. Bi-annual and annual programs don't carry a discount, but they do come with automated reminders, so the spring clean gets booked without you having to think about it.

Frequently asked questions

Can windows be cleaned outside when it's below zero?

Not well with water. Once the glass is below freezing, water can turn to a thin layer of ice before it runs off or dries, which leaves streaks and can freeze in tracks and gaps. Exterior cleaning works best on days that stay comfortably above zero, which is why it pauses for the coldest months in Montréal.

When is the last chance for exterior window cleaning in Anjou this year?

Exterior work runs roughly from March to November, so late October and the first part of November are usually the last practical window. The exact end depends on the weather each year. Booking early in that stretch gives you the best odds of mild, dry days.

Is it worth cleaning windows in the fall if winter will just get them dirty again?

For most homes, yes. A fall clean removes summer pollen, dust and spider webs before they bake onto the glass, and it means you start winter with clear windows during the months when daylight is shortest. Glass that goes into winter clean is also easier to get back to clean in spring.

Can interior windows still be cleaned in December or January?

Yes. Interior cleaning runs year-round since it isn't affected by outdoor temperatures. Interior glass is an optional paid add-on, so mention it when you get in touch.

Book the last outside clean of the season

Count your windows and pick your tier on the pricing page while there are still mild days left. If you want screens washed before storage, tracks cleared or interior glass done too, send us a message and list what you need.