Whether you’re using oil or water-based paint, you want to paint before it drops below 50 degrees Fahrenheit/10 degrees Celsius.
Both oil and water-based paints will thicken and lose viscosity in the cold. If the surfaces they’re trying to adhere to are cold, the paint may dry, but it won’t cure.
Oil vs Latex
On the cold end of the temperature spectrum, the 50-degree mark is consistent between latex and oil-based paint.
At the higher end, oil offers a bit more flexibility; oil-based paints can be applied and expected to cure effectively up to 90 degrees Fahrenheit.
Latex paints have an ideal application, drying and curing time between 50 and 70 degrees Fahrenheit.
Primer Vs. Paint
Primer will seem to dry more quickly. You should be able to touch a freshly primed wall after 60 minutes.
However, it will need to cure for at least 4 hours before you apply the top coat or you will risk pulling up the primer.
If you’re painting over wood that has been sanded and scraped, remember that warmth equals viscosity or flow.
To get primer to fully cling to, wrap-around, and cure against wooden clapboards, it’s a good idea to apply it with a nylon bristle brush.
With this tool, you can work primer fully into the surface and under the clapboard edges. The colder the primer and the surface are, the harder it will be to get good coverage.
The warmer air is, the more moisture it will hold. Very cold air is inherently dryer than warm air.
The trouble with painting in the cold is that it may seem that the paint is drying more quickly when the air is cold.
On outdoor painting projects, do your best to get the project done with enough curing time to be done before the lows dip below 50 degrees Fahrenheit.
As mentioned above, warm air holds more moisture. As the sun sets and the night cools off, that moisture will settle out.
If you’ve ever woken to frost or dew on your vehicle window, you understand how this settling will impact your painting project.
Cold mornings and a heavy dew or frost will alter your curing time. These conditions can also lead to a bloom or a milky “puddle” in your painted surface.
If you paint in the fall and the color blooms, you will be stuck with it until spring.
Drying Vs. Curing
Dried paint is not cured paint. Paint will dry in just a couple of hours, but it can take up to 4 weeks to fully cure.
Painting in early fall may not be the best option if you’re in a region prone to early freezes.
Some may consider warming up latex paint before applying it if they need to paint in the cold.
While this will make paint a bit runnier, it won’t increase the drying time and the surface of the paint may be marred by improper curing.
NOTE: Warming up oil-based paints can result in spontaneous combustion. Do NOT apply heat to oil-based paints.
Warm paint on a cold surface that will get colder once the sun goes down will not result in a quality paint job.
You may experience poor adhesion or color variations in the surface when the project finally cures.
Caulking and Sealing Projects
A quality paint job includes properly sealing up trim and caulking up gaps. You can caulk in 40-degree weather and still get the product to flow, but again, the curing time may be extended.
Cold caulk doesn’t flex as well as warm product, so you may end up using too much and making a gloppy job of it.
If you’ve got large gaps around windows and doors and must provide some type of seal, avoid spray foam and instead use ethafoam rod.
Spray foam is ideally applied at between 70 and 80 degrees; in fact, of all the products listed in this review, spray foam seems to be the most fragile product.
Ethafoam rod can be purchased in sticks or rods. Once you Gill the gaps with this, you can caulk over it when the weather warms up.
Ethafoam or backer rod is pretty durable and will not be any tougher to apply when it’s cold than when the weather warms up a bit.
Both brick and stucco can be effectively painted between 50 and 90 degrees Fahrenheit. A wooden house has a smaller temperature range; ideally, you want to paint when it’s between 60 and 85 degrees.
Of course, there are many regions of the country when these ideal temperatures are hard to manage.
If you do find days that feature these ideal temperatures, they may be followed up by an overnight rain.
Should you note the ideal temperatures coming up in the next few days but there is a risk of rain, remember:
- paint will dry in 2 to 4 hours, though it needs more time to cure
- your house has to dry for at least 4 hours after a rain to start painting again
- you’ll want to start on the side that gets plenty of sun to make sure you get good adhesion
If you have recently scraped paint off a wooden house and gotten a heavy rain, it may be best to let the raw wood dry for 24 hours if at all possible.
A great paint job can take several days, especially if you’re working in the spring when showers are a risk.
If you need to take time off work to get the project done, ask your boss for a bit of flexibility on arranging your start date so you can avoid temperature extremes and rain.