TL;DR
Most homes need exterior windows washed twice a year, in late spring after pollen drops and in early fall after summer dust settles. Interior glass runs on its own schedule -- two to four times a year, more where cooking or pets are involved. Screens get washed once a year, in spring, and always before the glass.
Why the calendar matters more than the frequency
Twice a year is the answer almost every source gives, and it is roughly right. The part that gets skipped is when those two washes should land, and that is where most of the wasted effort happens.
Windows get dirty from specific seasonal sources, and each source has a season. Pollen arrives in spring and coats glass in a yellow film that rain streaks rather than removes. Summer brings dust, irrigation spray, insect residue, and hard-water spotting. Fall drops leaf tannin and organic debris into tracks. Winter delivers rain, splash-back grit, and the interior condensation that stains frames.
Wash in the middle of the source season and you have redone it in three weeks. Wash right after the source season ends and the result holds for months.
When is the best time to wash windows?
Wash exterior windows twice a year: once in late spring once the heaviest pollen has fallen, and once in early fall after summer dust and before leaf drop and rain. Wash interiors two to four times a year on whatever schedule matches cooking, pets, and traffic. Wash screens in spring, before the glass.
The spring wash: after pollen, not during it
The instinct is to wash windows the first warm week. That is usually two to four weeks early.
During peak pollen, glass re-films within days, especially on the side of the house the wind favors. Waiting until the visible yellow stops accumulating on cars and outdoor furniture means one wash instead of three.
The spring pass covers screens first, then exterior glass, then interior glass, then sills and tracks. Doing screens before glass matters because rinsing a screen sends grit and debris straight down the pane, and doing it after means washing the glass twice.
The fall wash: after summer dust, before leaf drop
The second wash lands in early fall. Summer leaves a mix of dust, pollen residue, irrigation overspray, and insect deposits, and the fall wash clears it before the wet season arrives.
Doing it before leaf drop is deliberate. Leaves clog tracks and weep holes, wet leaves stain sills, and once the weather turns you lose the dry days that make exterior washing pleasant. It also means going into winter with clean glass, which matters because winter is when the light is worst and the windows stay shut.
Interior glass runs on a different clock
Interior glass is not driven by weather. It is driven by what happens inside.
A kitchen window near a range films with cooking grease and needs a degreasing wipe every month or two. Windows with dogs or kids get nose prints and handprints continuously. Bedroom and formal-room windows may look fine for six months.
Two to four times a year is a fair default for most interior glass, with the kitchen on its own faster cycle. The technique that keeps it from streaking is covered in how to clean windows without streaks.
Screens: once a year, and they need it more than you think
Screens hold a surprising amount of material -- pollen, dust, insect debris, and in some homes a grey film that dulls the view and reduces airflow.
Once a year in spring is enough for most homes. Remove them, label them so they go back in the right openings, brush them dry first, then rinse with low-pressure water and a soft brush with mild soap. Let them dry fully before reinstalling, since a damp screen against a frame is how frame mildew starts. If frames already show speckling, see how to clean mildew off window frames.
Never use a pressure washer on a screen. It stretches or tears the mesh and can pop it out of the frame.
Tracks, sills, and weep holes: twice a year, with the glass
Tracks are the part that causes real damage when skipped. Grit in a track wears the mechanism and makes a window hard to operate, and blocked weep holes at the bottom of a frame trap water inside the sill, where it rots wood and blisters paint.
Vacuum the track with a crevice tool, loosen packed debris with a stiff brush or an old toothbrush, then wipe damp. Check that the small drainage openings at the outer bottom edge of the frame are clear.
The weather rules that decide the day
Overcast beats sunny. Direct sun dries cleaning solution before you can squeegee it, and that is what produces streaks. An overcast, dry, mild day is ideal.
Avoid freezing conditions. Solution can freeze on the glass, and it is unpleasant work with no upside.
Avoid windy days. Wind dries streaks in and blows grit onto wet glass.
Wait a day or two after rain. Fresh rain leaves splash-back grit on lower panes.
When to hand it off
Ground-floor windows are ordinary work. Second-story exteriors, steep or awkward roof access, large fixed panes, and anything requiring a ladder on uneven ground are the point where most people stop, and reasonably so -- ladder falls are one of the more common home-maintenance injuries. What professional window work covers and what it costs in the market is laid out in a professional window cleaning guide.
FAQ
How often should windows be washed?
Twice a year for exteriors is the standard for most homes, in late spring and early fall. Interiors run two to four times a year depending on cooking, pets, and traffic. Homes near a busy road, agricultural land, construction, or heavy tree cover often need a third exterior pass.
Should you clean windows in spring or fall?
Both, and the timing within each season matters. Do the spring wash after heavy pollen has finished falling rather than at the first warm week, and do the fall wash after summer dust settles but before leaf drop. Washing during peak pollen means the glass films over again within days.
Do you wash screens or windows first?
Screens first. Rinsing a screen sends dust and debris down the glass, so cleaning the glass first means doing it twice. Brush screens dry, wash them separately, let them dry fully, and reinstall them after the glass is done and the tracks are clear.
Can you pressure wash windows?
No. Pressure can force water past window seals, damage failing glazing, tear screens, and drive water into the frame and wall. Exterior glass is washed with a soft brush or applicator, a squeegee, and low-pressure rinsing. Pressure washing belongs on siding and hard surfaces, at appropriate settings.
Why do windows streak when washed in the sun?
Sun heats the glass and evaporates the cleaning solution before it can be squeegeed off, leaving behind the dissolved soil and any residue in the product. Working on an overcast day, or on the shaded side of the house as the sun moves, is the single easiest fix for streaking.
What causes the water spots that will not come off?
Usually hard-water mineral deposits from irrigation spray or runoff, which bond to the glass over time and stop responding to normal cleaning. Prevention is redirecting sprinklers away from the house. Established mineral etching may need a specialist assessment, since aggressive abrasives permanently scratch glass.
Windows are the job most people happily hand off, especially the upper floor. If you want them on a schedule alongside the rest of the house, get a quote or read more about house cleaning services.
