Paint cures, it doesn't just dry. That distinction is the whole reason timing matters in North Carolina. A coating applied when the surface is too hot, too cold, or still holding moisture from last night's dew will look perfect for a season and then fail at the worst possible place: the south wall, the window trim, the spots you look at every day.
The best stretches around Henderson and the Triangle are generally late April through early June, and mid-September through October. Daytime temperatures sit in a comfortable range, overnight lows stay above the point where most acrylics stop forming a proper film, and the brutal afternoon humidity of July and August has backed off. Spring and fall also give us longer windows where the siding is out of direct sun, which matters more than the air temperature does.
Mid-summer isn't off the table, but it changes how we work rather than whether we work. We follow the shade around the house, start on the east side early, and stop painting a wall well before the surface gets hot enough to flash the coating off before it can level out. A thermometer pointed at the siding tells you more than the forecast does.
The real enemy in this part of the state is moisture, not cold. Morning dew on siding looks like nothing and ruins adhesion completely. If a wall was pressure washed yesterday, it may still be holding water inside the wood today, especially on a shaded north side under tree cover. We give it the time it needs, which occasionally means telling a customer we're not painting that wall until tomorrow.
Winter work is mostly interior for us, and that's a good thing. If you want your exterior painted in May, the conversation should happen in February. The crews that still have May availability in April are usually the ones you'd rather not hire.