What we check
- Work window: 4 hours, starting between 9 AM and 1 PM
- Temperature while working: 35–90°F required, ideally 50–85°F
- After you finish: stays at or above 35°F for 8 hours (required)
- After you finish: stays at or above 50°F for 8 hours (recommended)
- Humidity: at most 85%, ideally under 75%
- Dew point: air at least 5°F above the dew point, with no dew in the 4 hours after
- Wind: at most 15 mph, ideally under 10 mph
- Rain after: no likely rain for 12 hours (ideally 24 hours)
- Rain before: dry for 24 hours so surfaces are dry
These limits reflect typical manufacturer and industry guidance. Your product label always takes priority.
The best weather to paint outside
For standard exterior latex paint, look for temperatures between 50°F and 85°F, humidity roughly 40–70%, a light breeze, and a dry forecast. Many premium exterior paints are rated for application down to 35°F. If you're painting in early spring or late fall, check your can. This tool marks 35–50°F days as "Maybe" for that reason.
Above about 90°F, or on walls in direct sun, paint dries too fast, shows lap marks, and may not bond well. Paint the side of the house the sun has already left.
How long does exterior paint need before rain?
Most modern acrylic latex exterior paints can handle a light shower after a few hours in warm, dry weather, but they are far from cured. A heavy rain in the first several hours can wash out color, cause streaks, or leave a sticky film. Oil-based paint needs longer, often a full day or more.
This forecast requires 12 dry hours after you finish and warns if rain arrives within 24 hours. That buffer covers most products and conditions.
Dew point: the hidden reason exterior paint fails
When the air cools to its dew point, moisture condenses on your siding, even on a clear evening. If fresh latex paint gets dewed on before it sets, you can get surfactant leaching: tan, white, or glossy sticky streaks running down the wall. The surface should be at least 5°F warmer than the dew point while you paint, and the paint needs a few hours to set before dew forms.
That's why this tool checks the temperature-to-dew-point gap during your work window and the 4 hours after. In cool seasons, stop painting by mid-afternoon.
Prep tips for a paint job that lasts
- Wash siding a day or two ahead and let it dry completely (24–48 hours after pressure washing).
- Scrape loose paint, spot-prime bare wood, and caulk gaps before the finish coat.
- Work from top to bottom and keep a wet edge. Don't stop in the middle of a board or panel.
- Leave at least the recoat time on the label between coats, longer when it's cool or humid.
Frequently asked questions
What temperature is too cold to paint outside?
For most standard exterior latex paint, below 50°F is too cold. Many premium paints are formulated for application down to 35°F, but the temperature must stay above that minimum while the paint dries, including overnight.
Can I paint outside in high humidity?
High humidity (above about 85%) slows drying and raises the risk of dew forming on wet paint. Paint when humidity is moderate, start after morning dew has dried, and finish early enough for the paint to set before evening.
How long should paint dry before it rains?
Aim for at least 12 hours without rain, and ideally 24. Many latex paints resist a light shower after a few hours in warm, dry conditions, but heavy rain early can cause streaking and washout.
Can I paint if it rained yesterday?
Only once the surface is fully dry. Siding and trim in shade can stay damp long after rain stops. Give wood at least a full dry, sunny day, and check that there is no moisture in cracks or on the undersides of boards.