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Driveway Sealing Weather in Seattle, WA: 10-Day Windows & Best Months

In Seattle, the label math works from May through September: that's the stretch with 8+ workable days a month against typical driveway sealing rules. The single best month is July, averaging 27 days that clear every check — highs of 77°F, lows near 58°F, and a 13% daily rain chance. The strip above runs Seattle's live forecast; the table below ranks all 12 months.

GOOD — clears every rule MARGINAL — exactly one soft miss NO — a hard fail, or two soft

The rules this check uses

This table is the whole Seattle check: pail-consensus thresholds, the rising-trend requirement, and a 36-hour cure standing in for the labels' 24–48 spread.

Typical label thresholds for driveway sealing — the ruleset behind every Seattle verdict above.
CheckThresholdWhy it matters
Air temperature 55–90°F, and rising Checked across the working day, 8 a.m.–6 p.m., against Seattle's hourly forecast — not just the daily high.
Overnight low ≥50°F during the first 24 h The engine reads every overnight hour in the cure window, not just Seattle's forecast low.
Dry before ≤0.05" rain in the prior 24 h Asphalt must be fully dry; sealer will not bond to damp pavement.
Dry after <0.05" rain for 36 h after (48 h cool or shaded driveways want 48 h) Most sealers list 24–48 dry hours; this site checks 36.
Evening dew-point spread ≥5°F from 6–11 pm Scored on the worst hour between 6 and 11 p.m., when surfaces cool past the air.
Daytime humidity ≤85% Water-based sealer dries by evaporation; humid air stalls it.
Wind ≤20 mph (dust and debris in wet sealer up to 28 mph) Wind wrecks application first (drift, lap marks) and carries debris into wet work second.

Always follow your product label — formulas vary. These rows are the industry-typical range; the can in your Seattle garage is the contract.

Best months for driveway sealing in Seattle

Workable days in Seattle, WA: days meeting the temperature rules, discounted by NOAA rain odds — a 1991–2020 estimate, not a forecast.
MonthAvg highAvg lowRain odds/dayWorkable days 
January 49°F 37°F 60% 0
February 51°F 37°F 56% 0
March 55°F 39°F 56% 0
April 60°F 44°F 49% 0
May 66°F 49°F 38% 8
June 71°F 54°F 27% 22
July 77°F 58°F 13% 27
August 77°F 58°F 14% 27
September 72°F 54°F 28% 22
October 61°F 46°F 47% 1
November 53°F 40°F 58% 0
December 48°F 36°F 60% 0

Figure 107 workable days a year in Seattle, spread across May through September. Shoulder months turn on the overnight rule: an afternoon at 66°F passes, but the 50°F night floor is what actually opens the season in May. For the statewide picture, the Washington page compares peak months city by city.

The rain odds swing hard across the year — 13% of days in July up to 60% in December. Season the plan accordingly: prep in the wet months, apply in the dry ones.

Pouring before you seal? Concrete in Seattle trades the pavement-warmth rule for a 48-hour freeze watch.

Numbers above come from NOAA's 1991–2020 normals for Seattle Boeing Fld, Wa Us, 8.4 km from the city center — close enough that neighborhood microclimates (shade lines, river valleys, urban heat) matter more than station distance. See how these day counts are scored.

Seattle by the numbers

Prep checklist

  1. Wait for a rising pair: 55°F+ and climbing, first night over 50°F, 36 dry hours — in Seattle that pattern lives May through September.
  2. Run crack filler the previous afternoon — filler needs its own skin time before topcoating.
  3. Sweep to bare asphalt and kill the oil spots first — emulsion won't bond through either.
  4. Check yesterday, not just today: 24 h under 0.05" of rain. Seattle's July makes that nearly automatic at 13% rain-day odds.
  5. Tape the garage slab and sidewalk lines with edging tape — drips on concrete are forever.
  6. Pull thin passes with a squeegee/brush combo, back-brushing the texture as you go.
  7. Start early at the top of the slope: a July morning coat gets the whole 77°F afternoon to break before dew.
  8. Keep tires off through the full cure — with July nights at 58°F, shaded strips need the long end of 24–48 h.

Gear that saves a window

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FAQ

What temperature do you need to seal a driveway?

55–90°F and rising, with the first night at 50°F or better. The 'rising' part is why Seattle's May start matters: sealing on the front of a warm spell, not the back. Pavement lags air — a shaded slab can fail a passing afternoon.

How long after rain can I sealcoat?

24 hours after the last 0.05"+ rain, and only once cracks and shade strips are visibly dry — asphalt pores hold water after the surface grays out. In Seattle's December (60% rain days) that lookback eats most of the calendar; July barely notices it.

How long does driveway sealer take to dry before rain or cars?

Plan 36 rain-free, car-free hours (labels range 24–48; shade and cool nights need the long end). A 0.05"+ shower inside the window streaks the coat gray. July is Seattle's easiest month to find that window; December the hardest.

Can you seal a driveway in the fall?

Yes, until the nights quit. The 50°F overnight rule closes Seattle's season after September; the classic October mistake is a 62°F Saturday over a 41°F night. Spring restarts around May when pavement warms.

How often should a driveway be sealed?

When the surface tells you: graying, no beading, spreading hairlines — typically every 2–4 years. In Seattle, seal before the freeze-thaw season; December averages 36°F nights that pry open every unfilled crack. Fresh asphalt waits 6–12 months.

Best month to seal a driveway in WA?

July tops Seattle's table at 27 days clearing the 55–90°F-rising, 50°F-night, 36-dry-hour stack; July and August together carry the season. Check the WA state page for how the ranking shifts across the state.

Other projects in Seattle

Driveway Sealing nearby

Guides

Climatology: NOAA 1991–2020 normals via SEATTLE BOEING FLD, WA US (8.4 km from Seattle center, elevation 20 ft); live outlook by Open-Meteo.