I read from your site that exterior painting should be done when it's over 60° f. How long after application does this guideline apply....For example, the forecast calls of daytime temperatures in the mid-60's but overnight temperatures in the low 40's -Is that a "go" or a "no go"?
The 60° F guideline is ideal. The minimum application temperature on the label should be followed carefully. This typically is 50° F. for latex paints. We suggest these points:
Do not apply the paint if the air temp. is below the recommended minimum, or is predicted to drop below the minimum for the next 36 hours.
Do not apply the paint if the surface is below the minimum recommended temperature. For example, if the temperature in the night was 35°, and the air temperature is now up to the minimum recommended temp of 50 at 9:00 am, and you are painting aluminum siding, the siding itself is probably too cold.Not following these guidelines can cut years off the life of the paint job, before cracking and loss of adhesion set in. Oil based paints are more forgiving than latex in this regard, but lower temperatures will still retard their dry, which can result in dirt collection, especially if it gets windy.
Here is our summary statement on this: The extremes in temperature and sunshine should be taken into account when applying primers, paints and stains. Care must be taken that they can form a good film. This means they should not be applied at a temperature lower than the recommended minimum temperature for the product (typically, 50 degrees F.)... this includes temperature of the surface being painted; and application should not be done if the temperature is predicted to be below the recommended minimum anytime in the next 36 hours. Also, don't apply paints under conditions that will make them dry very quickly: do not paint in direct sunshine, and in warm, dry, breezy conditions.