La Crosse's humid-hour counts
In an average year at La Crosse, NOAA counts about 292 hours with the wet-bulb temperature above 73°F and about 1,002 hours above 67°F.
A wet-bulb reading captures heat and moisture together. The higher it runs, the less extra moisture the air can take up, and that is the property that matters to a painter: most house paint sold today is water-based, and it dries by handing its water to the air. This page looks at what that means on the job, indoors and out, without stretching the station figures past what they say.
Tacky, soft and slow
When the air is already holding plenty of moisture, a fresh coat stays wet longer. In general, that can bring:
- surfactant leaching, a sticky tan or glossy residue that weeps out of fresh latex in damp or dewy conditions, often on exterior walls and bathroom ceilings;
- blocking, where painted doors and windows stick to their stops when closed too soon;
- longer recoat times, so a job planned for a set number of days runs over;
- dust and insects settling into a film that hasn't skinned over.
None of that means the paint is bad. It means the schedule should follow the label's recoat and cure guidance rather than the clock. Ask your painter how they adjust their day when the air is heavy.
Mildew on the outside
Mildew grows on damp, shaded, dirty surfaces, and fresh paint over it fails. Before an exterior repaint:
- wash the siding and kill mildew with a cleaner made for it, then rinse;
- let the surface dry fully before primer;
- consider a paint with mildewcide for walls that stay shaded, if the maker offers one;
- cut back shrubs and vines touching the siding so air can move.
Our exterior painting page covers washing and prep in more depth.
Rooms that make their own humidity
Inside, the rooms to think about are the ones that add moisture: bathrooms, kitchens, laundry rooms and basements. Flat paint holds moisture and grime; a satin or semi-gloss sheds both and stands up to wiping. Many paint makers sell lines for bathrooms with mildew resistance built in. A working exhaust fan matters more than any paint, though. If a bathroom ceiling keeps peeling, the fix starts with ventilation, then paint. The paint sheens and finishes guide compares the options.
Basement walls
Painted masonry below grade can blister or shed if moisture is coming through the wall itself. A simple test is to tape a square of plastic sheet to the bare wall and see whether moisture collects behind it. If it does, the source needs attention before any coating, and ordinary wall paint isn't the answer; masonry coatings are made for that substrate. Ask the painter what product they would use and what prep it needs.
Lead-safe programs
EPA runs the RRP program in states it has not authorized; Wisconsin is on EPA's list of states that run their own EPA-authorized programs. If a job will sand or scrape old paint, ask how the painter will keep dust contained and how cleanup will be done at the end of each day.
Planning around drying time
- Book exterior work with slack in the schedule for slow-drying days.
- Ask for the product names, and read the recoat and cure times on their data sheets.
- Run fans and exhaust while interior paint dries, unless the painter advises otherwise.
- Keep doors and windows from closing hard against fresh paint until it has hardened.
- Expect bathrooms and kitchens to get a different product from bedrooms.
- Plan furniture and picture hanging around cure time, not just dry time.
Interior jobs are covered on interior painting, and price drivers on the pricing guide.