How To: Paint in Hot Weather

When the mercury starts rising and the temps change from comfortable spring weather to sweltering summer heat, a new set of challenges is upon all us looking to do some exterior painting. In a southern climate, it’s imperative that you learn how to paint in hot weather. The heat presents a unique challenge to painting, much like the cold does and it requires some different preparation.

My company has painted all kinds of old houses across the southern US and we are no stranger to hot weather. In this post, I’ll show you some of the tips and tricks I use to keep our paint jobs lasting longer than the typical paint job. It’s all in proper prep and understanding how to avoid the danger zones.

Problems & Solutions

The warmer and drier the weather, the faster your paint will dry. Manufacturers drying times are based on 77°F and 50% humidity and while we would all love to live in perfect weather like that, it is rarely the case when you are trying paint outdoors. To paint in hot weather effectively, you want to keep your working conditions as close to those optimal temps as possible. Since there is nothing you can do about the humidity levels outdoors, I won’t even broach that topic.

1. Avoid the Sun

The sun is your biggest enemy in the summer because it can super heat surfaces 20°F or more above air temps depending on the color of the surface and the exposure. Direct sunlight on freshly applied paint will often cause a lack of adhesion and the dreaded bubbles to form in the finish. No thank you!

The best way to protect your fresh paint from the sun is to strategically plan your paint job. Inspect the site and see what areas are in shade at what times of day. Starting on the South and West walls in the morning and moving to the North and East sides after lunch is a must. Also, pay close attention to the time of the year, since the sun in further South in the late spring and early fall. You wanna give the paint plenty of time to dry to the touch before the sun hits it.

Checking the surface temp is key, if it’s too hot to the touch, then it’s too hot to paint.

One other thing to note is that just because an area is shaded doesn’t mean that it isn’t too hot. If the sun was shinning on that East wall all morning and you paint it the minute it’s in the shade, it is still retaining a lot of heat energy that needs some time to dissipate and cool down. Checking the surface temp is key, if it’s too hot to the touch, then it’s too hot to paint.

2. Fight Evaporation

If you’re going to paint in hot weather, you’ll probably notice that you get gloppy and thick paint. That’s because the water is quickly evaporating in the can while you’re working. Thick paint goes on poorly and dries too quickly to level out or have good adhesion, which leaves you with a double whamming of ugly brush marked paint that will peel in short order.

So, what can you do about the problem evaporation creates? First, don’t ever let your paint sit in the sun, whether it’s in the back of your truck or in the yard, be vigilant at finding a shady spot for your paint supplies. Also, cover your cup of paint with a damp rag when you take a break or clean your brush.

Regardless of what you do, the water will continue to evaporate from your paint so adding water back into the paint up to 10% of volume will help it flow and not get it too watered down. You can also use extenders and additives like Floetrol for water-based paints and Penetrol for oil-based paints. Oil based paints suffer the same issues as water based except that it’s paint thinner that is evaporating faster rather than water. For more info on how to work with oil-based paints read my previous post here.

Check out the video below for a quick tutorial on using these extenders and some other techniques to help you avoid brush marks on your paint work.

3. Use Ice

No, don’t add ice to your paint, but yes do add a couple pieces of ice to your paint cup before you put your liner in. A couple pieces of ice will keep your paint just cool enough in the cup that it will slow evaporation and give you a little extra working time as you apply. Be aware that too much ice makes for paint that is below its optimal temp of 70+ degrees, but just the right amount will keep it cool enough that it actually cools the surface of the building that might be in the 90s. It’s a simple and free fix.

4. Avoid the Rain & Sprinklers

Depending on where you live, the summer may be the dry months of the wet months, so this is good advice no matter when you paint. You must plan your paint schedule around the weather and make sure your paint has at least 2-3 hours to dry before any rain is scheduled to roll in. That seems simple enough for most people, but what you don’t think about is the sprinklers.

In the summer, the sprinklers are running in full force for most homes and I’ve seen many paint jobs ruined by a misplaced sprinkler head. Before you even break out the paint turn the sprinklers on and make sure nothing is spraying water close to the area you will be painting. If the design of the sprinklers makes this difficult to accomplish, then you really should have them redirected by a pro or at the very least make sure the sprinklers are turned off for a few days before and after your exterior painting project is happening.

I hope these tips from a Florida boy help you paint in hot weather like a pro. Nothing protects your house better than a quality paint job and doing it right means you won’t have to do it again for a long while.