PaintDay: Painting Weather

PaintDay tells you the hours today when a coat will actually hold, and what closes the window.

Paint fails when the surface sits within about 3 °C (5 °F) of the dew point. A film of condensation forms under the coating and it peels inside two years. A sunny 18 °C morning still has a north wall below the line, and nobody can see it. PaintDay works out the surface temperature of the wall you are painting from its direction, its colour, the sun, the cloud and the wind, then compares it to the dew point through the whole day.

What you get
• A start and an end time instead of a mood: 08:20 to 16:30, 8h 10m of painting time.
• The reason the window closes: rain at 17:00, air gone too wet, the wall dropping under the dew point, or a coat that would still be wet when the evening damp arrives.
• A chart of surface temperature against dew point with the safe margin shaded, so the failure nobody can see becomes the one thing you cannot miss.
• Seven days ahead, so a job is planned instead of guessed.
• A home screen widget carrying today's answer, and a verdict every morning at 06:30.

Every coating has its own rules
Exterior wall paint, oil-based gloss, deck paint, wood stain, concrete and brick sealer, garage floor epoxy, spray paint and primer, and thick waterproof coatings. Each one carries its own temperature range, dew point margin, humidity and wind limits and rain-free hours, and the app shows which limits it used. Your own product data sheet always wins, so every limit is editable.

Measured the wall with an infrared thermometer? Type the reading in and it replaces the estimate for the rest of the day.

Built for exterior painters and decorators, deck and fence work, garage floors, spray shops, and anyone who has watched a coat fail for reasons an ordinary weather app never mentions.

Forecast data by MET Norway (CC BY 4.0). Coarse location only, no account, no tracking. Works in °C and km/h or °F and mph.