Two problems from opposite directions
Exterior paint can fail because it dries too slowly or because it dries too fast. NOAA's figures for the Dothan station point at both.
NOAA's engineering weather data for Dothan counts about 1,618 hours a year above 80°F and about 112 hours above 93°F in an average year. In an average year at Dothan, NOAA counts about 1,776 hours with the wet-bulb temperature above 73°F and about 3,503 hours above 67°F. These are long-run counts for the Dothan station, not a forecast for your job.
When paint dries too fast
Hot surfaces pull water out of latex paint before it can level. The results include lap marks where wet paint meets paint that has already set, brush marks that never flow out, and weaker adhesion because the coat didn't have time to wet the surface properly. Dark siding and walls in direct afternoon sun get far hotter than the air around them.
Ways painters manage this:
- Following the shade. Many crews paint each side of the house after the sun has moved off it.
- Smaller sections. Working from one natural break to the next, a corner or a window, keeps a wet edge.
- Reading the label. Most paints list a maximum surface temperature as well as a minimum.
- Product choice. Some products are made for warmer application; ask whether the painter uses one.
When paint dries too slowly
High wet-bulb hours are the opposite problem. Dew on the siding in the morning, moisture settling back onto fresh paint in the evening, and still, heavy air all slow drying. A coat that gets wet before it firms up can show streaks or a sticky residue. On many days a crew has to fit each coat between the dew drying off and the evening moisture returning, while staying out of the hottest sun. That window is narrower than the hours on the clock suggest, which is why a realistic schedule often has more days in it than you might expect.
Rain and wind
NOAA's engineering weather data for Dothan lists a 50-year basic wind speed of 100 mph (3-second gust at 33 feet), a 100-year rainfall rate of 4.3 inches per hour and about 14 freeze-thaw cycles in an average year. The wind and rain figures are design values used for buildings. For paint, heavy rain is a test of sealing: caulked joints, window heads and the seams where trim meets siding. The freeze-thaw figure is a reminder to look at horizontal surfaces, like sills, steps and rails, where water sits in cracks.
Color and heat
Darker exterior colors absorb more sun and run hotter than light ones. That means more movement in wood siding and trim and more stress on the paint film. Some paint lines offer formulas meant for deep colors in strong sun; ask whether the color you like comes in one. Our guide to paint sheens and finishes also covers how sheen changes the way a color reads outdoors.
Indoors
Inside, air conditioning keeps the air drier and cooler, and paint generally behaves better for it. Rooms that run warm, like a sunroom or a room over the garage, can still be tricky; ask whether the crew wants to paint them early in the day. Bathrooms add moisture of their own, and a finish made for damp rooms holds up better there. See interior painting for how a room is prepared.
What to ask before work starts
- In what order will you paint the sides of the house, and why?
- What are the label limits for the product, hot and cold?
- How do you handle dew in the morning and moisture in the evening?
- Is caulking at windows, doors and trim joints included?
- If a storm interrupts the job, how is unfinished work protected?
- Will you prime any bare wood before the finish coats? See the exterior painting page for why that matters.