What's the Ideal Outdoor Temperature Range for Using Exterior Paint?
It can make the difference between a job well done and a redo
By Tanya A. Christian
If you’re tempted to kickstart your spring cleaning list by doing some exterior painting, have a look at what your local temperatures are meant to do before you start. Water-based exterior paint requires certain conditions to cure—or fully harden—properly. If it doesn’t do that, you might be repainting your home’s exterior sooner than you planned.
“It should be at least 50° F when you’re applying the paint and shouldn’t drop below 32° F at night for several days after,” says Rico de Paz, who oversees Consumer Reports’ paint tests.
Even if it’s warm during the day, the paint won’t form a good film if temperatures drop too low at night. Paint needs several days to cure, and as the temperature dips, dew can form on surfaces and cause the water in the paint to evaporate too slowly. That affects how the paint holds up over time, including how well it resists cracking. Colder temperatures and moisture on the surface can also result in staining or mildew.
Depending on your local conditions, repainting can be a great part of your spring cleaning projects for the year. According to de Paz, spring and fall are the ideal seasons for painting just about everywhere in the country. “The weather is warm and the sun is not strong enough to overheat the surface that you are trying to paint,” he says. There’s also less likelihood that you’ll encounter temps dipping too low.
If you’re down south in a state like Florida, you could extend painting into winter. But watch the daily lows to be sure that there’s no chance of the temperature dropping below 40° F anytime over the next couple of days.
Some manufacturers now claim that certain paints will cure in temperatures as low as 35° F.
And what about an upper limit? For summer days—say, when temperatures hit 90° F—there’s no hard and fast rule about how hot is too hot outdoors. You will, however, want to pay attention to the surface temperature of the exterior walls of your house.
“If you can’t keep the palm of your hand on the exterior wall of your house for more than a few seconds, it’s too hot to paint,” de Paz says.
Check the label on the paint can for any instructions on the ideal temperature range, and follow de Paz’s tips, below, for how to prep for a DIY exterior paint job.
Prep Before You Paint
Follow these steps:
Protect other surfaces. Cover plantings, air conditioners, and exhaust vents with drop cloths. Tie back shrubs and tree limbs.
Scrub, then patch. Dirt, mildew, and chalky old paint prevent fresh paint from adhering properly. And if your house was built before 1978, there might be lead paint below the surface. (See CR’s step-by-step guide for using a test kit to check for lead paint.) In that case, you’ll need to use a certified lead-abatement contractor to prep the surface. Otherwise, scrub the surface with a wire brush or scrub pad, or very carefully with a pressure washer, and clean with a detergent such as Red Devil TSP.
Remove mildew. Mix a solution of chlorine bleach and water, or use a commercial cleaner. Wearing gloves, a mask, and eye protection, scrub away the mildew. Scrape out rotted areas and fill them with wood filler, then sand smooth. Allow to dry for several days before painting.
Caulk and prime. Scrape away dried and cracked caulk around windows, doors, and trim. Apply fresh acrylic caulk where needed. Prime bare wood using the primer recommended by the paint manufacturer, or skip priming by using a high-performing self-priming paint.
Replace cracked or rotted boards. Water could still seep in if you merely fill and repair cracked or split boards.
How CR Tests Exterior Paint
To determine a paint’s durability, we apply two coats to pine boards. Then we mount the boards on angled racks on the roof of our headquarters in Yonkers, N.Y., to see how well the paint withstands the elements. Then? We wait.
Because the boards are angled (not vertical as they would be on a house), they’re more exposed to light and the elements. Each year of testing is equivalent to about three years on vertical surfaces. Three years later, our results give you an idea of how the paint will look after nine years. We also test for mildew resistance by placing painted panels on vertical racks in a shady area of our campus.
Options in our exterior paint ratings that sell for less than $25 per gallon include finishes from Color Place, Glidden, and Valspar. Paints in the $25 to $48 range include those from Behr, Clark+Kensington, Glidden, HGTV Home, and Valspar. And you can spend $68 or more for a gallon of Benjamin Moore or Sherwin-Williams paint.
CR members can keep reading for ratings and reviews of the exterior paints that scored 72 or higher (out of 100) in Consumer Reports’ tests. All are self-priming, but be sure to check the can for situations when priming is advisable.
For more details, check our paint buying guide as well as our ratings for exterior and interior paint.
5 Top-Ranked Exterior Paints From CR's Tests
Exterior paints have improved over the past decade. Our tests show that, generally, they’re more durable and less prone to cracking and fading. But they seem to be less resistant to dirt buildup.
How to Paint
Do you have some painting projects planned for your home? On the “Consumer 101” TV show, Consumer Reports expert Rico de Paz shows host Jack Rico how to give walls the perfect coat.
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Consumer Reports is an independent, nonprofit organization that works side by side with consumers to create a fairer, safer, and healthier world. CR does not endorse products or services, and does not accept advertising. Copyright © 2022, Consumer Reports, Inc.
