Heat is the condition to plan for
NOAA's normals for its Laredo 2 station average about 177.6 days a year with a high of 90°F or more, including about 74.2 days at 100°F or more. The same station's normals average about 4.7 days a year with a low of 32°F or below. So when a painter in Laredo plans an exterior, the cold limit on the can rarely decides the schedule. The hot limit, and how hot the wall itself gets, usually does.
The wall is hotter than the air
Paint labels give a range of temperatures for application, and many specifically mention the surface temperature. A wall in direct sun, especially a dark one, can be much hotter than the air reading on your phone. Paint that goes onto an overheated surface can:
- Dry before it levels, leaving brush and roller marks.
- Show lap marks where fresh paint meets an edge that has already set.
- Blister, as solvent or water tries to escape through a skin that formed too fast.
- Bond poorly, because it never had time to wet the surface properly.
An infrared thermometer settles the question in seconds. Ask if your painter uses one.
Working with the sun
The fix is mostly scheduling:
- Start each day on the walls the sun hasn't reached yet, and follow the shade around the house.
- Leave the sunniest walls for later, after the sun has moved off them and they've had time to cool.
- Paint smaller sections so you can keep a wet edge.
- Shift hours earlier on the hottest days. Some crews start at first light and stop by mid-afternoon.
This can make a job take more calendar days than the square footage suggests. A painter who plans around it is protecting the finish.
Color, sheen and product
Dark colors absorb more sunlight and run hotter, which can stress the film and fade faster. Light colors reflect more. If you love a dark color, ask about products made for heat-absorbing colors, and consider using it on trim or doors rather than the whole body of the house.
For sheen, flatter finishes hide surface flaws on walls; satin and semi-gloss resist dirt and suit trim and doors. Our paint sheens and finishes guide explains the choices, and the exterior painting page covers products.
Some manufacturers sell formulas or additives that slow drying for hot conditions. Read the label or ask the painter what they'll use.
Prep still comes first
Heat doesn't excuse poor prep. Washing removes dust and chalk; scraping and sanding remove loose paint; caulk seals the joints; primer goes on bare wood and patches. Paint over chalk or dust simply flakes off later. Washed surfaces dry faster in heat, which helps, but wood should still be dry through before primer.
Inside in the heat
Indoors, air conditioning helps paint dry evenly. Keep it running, but avoid blowing cold air directly on fresh paint, and ventilate as the label asks. Our interior painting page has more.
Older paint and lead
If your house was built before 1978, some layers of paint may contain lead. Under EPA's Renovation, Repair and Painting Rule, anyone paid to do work that disturbs paint in homes, childcare facilities and preschools built before 1978 must hold RRP certification, firms included, even sole proprietorships, and their workers must be trained in lead-safe work practices. Before scraping or sanding, ask the painter whether the firm holds RRP certification.
Before you hire
Ask each painter:
- Which walls will you paint at which times of day?
- How do you check surface temperature?
- What product and sheen do you suggest for each surface, and why?
- What's included in prep?
The pricing guide explains what drives a painting price.