What to clean and when in a Bellevue home, based on NOAA normals for the wet months and the dry summer, a pollen chart that starts in January, light winter snow and late summer smoke.
Most cleaning calendars are written for places with a hard winter and a single burst of spring pollen. The Eastside runs on a different rhythm: a long gray wet season, a short dry summer, trees that pollinate in midwinter and the occasional smoke week when the windows have to stay shut.
This calendar uses the NOAA 1991 to 2020 normals for Seattle-Tacoma International Airport, the closest normals station to Bellevue, and the Seattle area pollen chart from the Northwest Asthma & Allergy Center. Use it to time the bigger jobs and to decide when a recurring plan deserves an extra visit.
A normal year at Sea-Tac brings 39.34 inches of precipitation spread over about 156 days. November is the wettest month at 6.31 inches. July gets only 0.60 inches and August 0.97, with highs near 77 degrees, and the airport averages just 3.8 days a year at 90 degrees or above. Winter is mild but not snow free: normal snowfall is 6.3 inches, nearly all from December through February, with about 25 nights a year at or below freezing.
The pollen year starts early. Hazelnut runs from January into February, alder from February into May, cedar and juniper from February through June, birch, cottonwood and poplar in March and April, grass from April into September with a peak in May and June, and weeds from May through September.
This is the darkest and dampest part of the year. Sea-Tac averages about 34 days with a tenth of an inch or more of precipitation across these three months, and winter highs sit around 47 to 50 degrees. Cold glass gathers condensation, so wipe window sills and tracks every week or two before the moisture leaves a dark line in the corners.
Most of the year's light snow falls now. When it does, the grit and de-icer used on driveways and walks comes in on boots. Keep a boot tray by each door and mop entries soon after a snowy day so the residue does not dull wood floors.
Allergy sufferers should not wait for spring. Hazelnut pollen shows up in January and alder in February, so wash bedding more often and vacuum upholstered furniture through these weeks.
Alder, cedar and juniper are still going, and birch, cottonwood and poplar join them in March and April. A fine yellow-green layer settles on sills, porch furniture and car hoods. The Northwest Asthma & Allergy Center notes that rain can lower the count, so the drier days in this stretch are the ones to keep windows down.
Once the wettest months are behind you, this is the time for the big reset. Clean window screens and tracks, wash entry mats, and book a One-Time Deep Clean to clear what the winter left on baseboards, blinds and fan blades. Grass pollen begins in April, so a second pass on soft furnishings in May is worthwhile.
Summer is the dry season. Rain is scarce, the days are long, and most homes air out with windows up. Grass pollen peaks from May through June and weed pollen continues all summer, so dusting matters more than mopping now. Wipe sills, ledges and electronics weekly in allergy households.
The Puget Sound Clean Air Agency says wildfires typically burn in the warmer, drier months and expects more smoke to reach Puget Sound. On smoke days it suggests keeping windows and doors closed and using a HEPA filter in an air cleaner or the HVAC system. When the air clears, wipe surfaces with a damp cloth rather than dry dusting, and replace or clean filters.
Hot days are rare on the Eastside, about 3.8 a year at 90 degrees or above, so the summer job is dust rather than sticky humidity. Any fan that runs through these weeks, ceiling or portable, collects a gray coat on its blades and grille fast.
Weed and grass pollen fade by the end of September, and the rain returns in October. By November, the wettest month, entries and hallways take a beating from wet shoes, dogs and fallen leaves. Put down washable runners, set up a spot for wet coats away from carpet, and consider moving from bi-weekly to weekly visits until the new year.
Fall is also a good time to look at the rooms where moisture lingers. Washington's Department of Health notes that mold tends to grow in rooms with high water use and where warm, moist air meets a cool wall, and recommends exhaust fans in bathrooms, kitchens and laundry rooms. Clean fan covers and check that each fan actually pulls air before the damp months settle in. The rain and mildew guide goes into more detail.
The questions Bellevue homeowners ask most often about this topic, answered plainly.
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