Best Temperature for Exterior Painting in WA

Quick Answer

Ideal Ambient: 55–75°F Surface & Air ≥ 50°F Humidity 40–70% Dew-Point Margin ≥ 5°F No Rain 24 Hrs

Why Temperature (and Dew Point) Matter in Washington

Washington’s coastal marine climate brings frequent clouds, cool nights, and damp mornings. In summer, UV is intense; in shoulder seasons, temps swing and dew forms early. Paint films need enough warmth and time to coalesce, release water/solvent, and build proper film thickness. If it’s too cold or too damp, you risk poor adhesion, surfactant leaching, lap marks, or peeling the first winter.

Ideal Ranges for Exterior Painting

Reading a WA Forecast the Right Way

Look beyond the high/low. Check hourly temperature, humidity, wind, and dew point. If you’ll be painting late afternoon, confirm that sunset temps won’t drop near the dew point before the film sets. Shade sides cool faster and collect evening condensation first — paint them earlier in the day.

Spring, Summer, Fall: What’s Best?

Spring (April–June)

Milder temps, but showers and damp mornings are common. Start late morning after surfaces dry. Use low-temp rated products if nightly lows are in the 40s–50s.

Summer (July–September)

Reliable window. Avoid hot sun on dark siding; paint façades as they move into shade. Watch afternoon sea breezes that can cool and raise humidity quickly.

Fall (September–October)

Great temps, but days shorten and dew sets early. Paint earlier, allow longer cure, and avoid late-day second coats if temps will drop rapidly.

Surface Temperature vs. Air Temperature

Dark fiber-cement or wood can run 10–20°F hotter than the air in full sun; north elevations can be 5–10°F cooler. Use an IR thermometer. If the surface is hot to the touch, wait for shade; if it’s clammy or cool near dew point, delay until it warms and dries.

Humidity, Dew Point, and Overnight Lows

High humidity slows water evaporation from latex paints. When the surface temp drops within ~5°F of dew point, moisture condenses. That can leave surfactant streaks or a blotchy sheen. Plan coats so the film sets before the evening temperature slide.

Cold-Weather Painting (When You Must)

• Choose low-temp formulations rated down to 35–40°F.
• Paint during the warmest part of the day on sun-exposed elevations first.
• Extend recoat windows and allow extra cure time.
• Use moisture meters for questionable wood.

WA Substrates and Temperature Sensitivity

Painter’s Checklist for a Good Weather Window

• ✔ Substrate dry (post-rain dry-out verified)
• ✔ Ambient & surface within spec for product
• ✔ Dew-point margin ≥ 5°F through evening
• ✔ No rain in forecast for at least 24 hours
• ✔ Plan façade order by sun/shade to avoid hot or condensing surfaces

Need a Weather-Smart Plan?

We schedule projects around PNW weather, verify substrate moisture, and select coating systems built for Washington homes. If you want a finish that holds up through wet winters and sunny summers, we’ll plan it right from day one.