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Roof Coating Weather in Washington: Best Months by City

Roof Coating season in Washington, city by city: peak months, season boundaries, and annual workable-day counts from NOAA 1991–2020 normals. Tacoma leads with 165 workable days a year; Marysville runs the shortest at 97.

Washington is not one climate: Tacoma banks 165 workable roof coating days a year while Marysville gets 97 — a spread the table below itemizes month by month. Season boundaries mark the first and last month averaging 8+ workable days against the label rules (50–90°F, nights 40°F+).

Statewide, August is the strongest month — it tops or ties the table in most listed cities. The live strips on each city page decide the week; this table decides the month. Scoring rules: methodology; the national playbook: the roof coating guide.

Cities in Washington

Peak months and season boundaries from NOAA 1991–2020 normals; season = months with at least 8 workable days.
CityPeak monthsSeasonWorkable days/yr
Seattle Jul, Aug, Jun April–October 159
Spokane Aug, Jul, Sep May–September 127
Kennewick Sep, Jun, May April–October 140
Bremerton Aug, Jul, Sep April–October 139
Tacoma Aug, Jul, Sep April–October 165
Olympia Jul, Aug, Jun May–October 125
Vancouver Aug, Jul, Sep April–November 160
Marysville Aug, Jul, Jun May–September 97
Bellevue Jul, Aug, Jun April–October 158
Yakima Sep, Jun, May May–September 107
Kent Aug, Jul, Sep April–October 157
Bellingham Aug, Jul, Sep April–October 145
Everett Jul, Aug, Jun April–October 137
Spokane Valley Aug, Jul, Sep May–September 127
Renton Jul, Aug, Jun April–October 158
Federal Way Aug, Jul, Sep April–October 165
Kirkland Aug, Jul, Sep April–November 153
Auburn Aug, Jul, Sep April–October 157
Wenatchee Sep, Jun, May April–October 145
Pasco Sep, Jun, May August–October 104

The rules behind these numbers

Typical label thresholds for roof coating — the single ruleset used by every check on this page.
CheckThresholdWhy it matters
Air temperature 50–90°F Acrylic and elastomeric coatings want 50°F+ during application and initial cure.
Overnight low ≥40°F during the first 24 h Water-based coatings can be ruined by a cold, damp night before they skin over.
Dry before ≤0.05" rain in the prior 24 h; watch back to 48 h The membrane must be dry — coatings trap moisture that later blisters.
Dry after <0.05" rain for 24 h after (48 h thick coats want 48 h) Rain inside 24 hours washes uncured coating into gutters.
Evening dew-point spread ≥5°F from 6–11 pm Roofs radiate heat at night and hit the dew point before anything else in the yard.
Daytime humidity ≤85% Humid air slows water-based coatings dramatically.
Wind ≤15 mph (roller only, no spray up to 20 mph) Wind on a roof is a safety limit first and an overspray limit second.

Always follow your product label — formulas vary. The table above is the typical range across major manufacturers, not a promise about your can.

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