The Best Temperature to Paint Outside

Everyone knows you shouldn’t paint outdoors on a rainy day, but what might not be as obvious is that you shouldn’t paint when it’s too hot or too cold. Consider this scenario: You’ve finally been able to carve out a weekend from your schedule to freshen up the siding or exterior trim with new paint, but Mother Nature has decided to send a heat wave your way. Are you better off devoting the time you set aside for another project? Maybe so.

“Painting in non-optimal temperatures can result in several issues,” professional painter Ryan Parr explains. “Poor adhesion can cause the paint to peel and flake, and uneven drying can lead to visible streaks, brush marks, or roller marks. The longevity of the paint job may be reduced, requiring more frequent touch-ups or repainting, and surface defects such as blisters and cracks can compromise the appearance and protection of the painted surface.”

Exterior paint products are designed to withstand any type of weather once they dry and cure, but they’re vulnerable when freshly applied. You probably don’t want to spend your weekend painting only to have to scrape off the paint and redo it in a few months, a job that could easily take twice as long.

This post explains the optimal temperature and humidity conditions to ensure your paint goes on smoothly and provides the appearance and protection you expect.

How Temperature Affects Drying Time

Every can of paint includes three ingredients: binders that protect the painted surface, pigments that add color and a solvent that makes the paint a liquid. When you spread the paint, the solvent evaporates, leaving the binders and pigments behind. In optimal conditions, solvents take from two to four hours to evaporate, but the binders don’t provide full protection until they have cured, which can take up to 24 hours or more, depending on the product.

When is it too hot to paint?

Solvents evaporate more quickly as the temperature rises, and on excessively hot days, they can evaporate before the binders have a chance to harden. “When the temperature rises above 90°F (32°C), the paint can dry too quickly, leading to poor adhesion, visible brush strokes, and roller marks,” warns Parr. “High temperatures can cause the paint to form blisters, which can pop and peel away, and the paint may not cure properly, resulting in a brittle surface that can crack easily.”

When is it too cold to paint?

The opposite happens when you paint outdoors on a cold day (temperatures below 50 degrees). The solvent takes longer to evaporate than it should, which results in a sticky or tacky surface for an extended period of time. The paint doesn’t adhere properly, eventually flaking or peeling. What’s more, says Parr, cold temperatures can increase the likelihood of condensation forming on the surface, which can interfere with paint application and drying.

The Optimal Temperature for Painting

The best temperatures for exterior painting happen to be those that are most comfortable for painters to work outdoors — between 50°F (10°C) and 85°F (29°C), according to Parr. This makes it easy to tell if temperature conditions are right. If you have to wear a coat, gloves and a hat outdoors, it’s probably too cold to paint. Conversely, if you can’t be outside in a T-shirt without breaking into a sweat, it’s probably too hot.

If the temperature is a few degrees below 85 degrees and time is of the essence, you might want to give outdoor painting a shot. However, if you do, avoid painting in direct sun. While the air may be cool enough for the paint to dry evenly, the surface you’re painting probably won’t be, and you risk cracking, blistering and other defects.

These temperature limits are rules of thumb; like all rules, they have exceptions, so check the label on the product you’re using. Some products, such as Glidden Premium exterior paint, are designed to dry evenly at temperatures as low as 35°F (1.7°C). Even these products will likely show defects if you use them when it’s too hot.

How Humidity Effects Painting

High humidity can inhibit evaporation, slowing drying even more on a cold day. On a hot day, excessive humidity can cause streaking, blistering, peeling and brush marks, especially if you’re using a water-based product. Ultra-low humidity isn’t much better. It speeds up evaporation and worsens the problems you encounter when the temperature is too high.

In general, you’ll get the best results if you paint in moderate humidity between 40 and 70 percent.

Can I Still Paint If It’s Too Hot or Cold?

So, you’ve planned to paint this weekend, but the weather isn’t cooperating. Do you have to scrap the project and reschedule? Not necessarily.

“Plan your painting schedule to work during the cooler parts of the day in hot weather and the warmer parts of the day in cold weather,” advises Parr. On hot days, paint in the early morning or late afternoon when temperatures are cooler, and avoid direct sunlight. On colder days, paint as early in the day as you can to prevent dew from forming overnight on freshly painted surfaces.

Above all, Parr advises checking the weather forecast and aiming for a stretch of mild weather to ensure ideal conditions for drying and curing.

About the Expert

• Ryan Parr is the owner and president of Nashville Painting Professionals, founded in Nashville TN in 2020. In 2022, Parr expanded his venture to Charlotte, N.C. and founded Charlotte Painting Professionals.