From LF Builders, the renovation company behind this forum. Data sheet figures checked October 31, 2026; manufacturers revise them, so check the sheet for your exact product code.
Short answer: It depends on the can, not the calendar. Several premium exterior acrylics now list a minimum of 35°F (1.7°C). Sherwin-Williams Duration and Benjamin Moore Aura’s current Canadian data sheets both do. Older sheets, and many other products, set 40°F or 50°F. The minimum applies to the air, the surface and the paint, and the paint has to stay above it while it dries, so the overnight forecast matters more than the afternoon high.
What two common exterior paints say
| Product | Minimum | Conditions on the sheet |
|---|---|---|
| Sherwin-Williams Duration Exterior Acrylic | 35°F (1.7°C) | Air, surface and material all above 35°F and at least 5° above the dew point. Don’t apply if temperatures may drop below 35°F within 48 hours. Large metal siding and unfilled block need 50°F. |
| Benjamin Moore Aura Exterior (Canadian sheets, e.g. F629, F634) | 1.7°C (35°F) surface | Don’t apply below the minimum air or surface temperature. Cool, humid weather lengthens dry, recoat and service times. Some older US sheets list 40°F. |
Primer is its own product
Your topcoat’s minimum isn’t necessarily your primer’s. Read the primer’s data sheet too and work to whichever of the two is stricter; a primer that never cured properly takes the topcoat with it.
Fall checklist for a late exterior job
- Check the 48-hour forecast, not today’s high. Frost or freezing overnight is what ruins a coat that looked fine at 3 p.m.
- Measure the surface, especially north faces and anything in shade. Siding can be colder than the air.
- Stay 5° above the dew point, or follow what your product’s sheet says. Moisture settling on paint that hasn’t set yet is a common reason late-season coats look blotchy or cure poorly.
- Start after the morning dew burns off and stop early enough for the paint to set before evening.
- Expect longer recoat times in cool, damp weather, and plan the second coat around that.
Painters, weigh in
- What’s the latest date you’ll start an exterior job in the GTA, and what product do you reach for in late October?
- Have you seen a late-season job fail? What went wrong: dew, frost, primer, or the wrong product?
