By Absolut Painting · Published October 27, 2026 · No prices in the guides
The temperature window
Most exterior latex paints want the air and the surface above a minimum temperature while they are applied and for several hours after, and the labels give that figure. Some low-temperature formulas from Benjamin Moore and Sherwin-Williams allow application on cooler days, which stretches the season at both ends. The number that catches people out is the overnight low, not the afternoon high. A warm day followed by a cold night can stop a coat curing properly, and it shows as a chalky or patchy finish later.
Hot days bring the opposite problem. Paint on a south wall in full July sun flashes dry before it levels, which leaves lap marks. The crew follows the shade around the house for that reason.
Dew point and humidity
The second number is the dew point. When the surface temperature falls to the dew point, moisture condenses on the wall, and a coat that has not set gets a dull, streaky surface that can fail early. On humid summer days in the GTA the surface and the dew point are closer than they look, especially on a shaded north wall in the late afternoon.
The practical rule is to start after the morning dew has burned off and stop early enough that the last coat has set before evening. Rain in the forecast within a day of application is a reason to wait. A good crew reads the forecast and the wall, not only the calendar.
Spring, summer and fall in the GTA
Spring is the busiest booking season, and the weather is the least settled. Late May and June are usually dependable. In July and August the limit is sun and humidity rather than cold. September is often the best month of all, with warm days, dry air and cooler nights still above the minimum.
- Late April to mid-May: possible with low-temperature products and a dry week.
- Late May to June: dependable, book early.
- July and August: good, with shade and humidity managed.
- September to early October: often the best conditions of the year.
- Mid-October onward: closing, product and forecast dependent.
Brick, stucco, wood and aluminum siding
The substrate decides the preparation and the product. Brick needs washing, any loose mortar repointed, efflorescence treated, and a masonry primer or an elastomeric or breathable coating so the wall can still let moisture out. Painting brick is a long-term decision, because it does not come off easily. Stucco needs cracks filled with a flexible filler and a primer suited to masonry before a coat that can move a little with the wall.
Wood is scraped, sanded, any bare spots primed, and caulked at the joints before two coats. Rotten boards are replaced, not painted. Aluminum siding is washed to remove chalking, which is the powder that comes off on your hand, and then primed with a bonding primer before a coat of exterior acrylic. Done that way it holds well. Skipping the wash is the usual reason a painted siding job peels.
How the preparation runs on site
Every exterior job starts with a wash, by hand or pressure, and a day for the surface to dry. Then scraping, sanding and spot-priming on wood, repairs on masonry, and caulking at windows, trim and joints. Gardens and walkways are sheeted, windows and fixtures masked. The paint goes on in two coats, following the shade around the house. The job ends with a walk around the property with you before the ladders are loaded.