Painting in cold weather is not always recommended!
It's important to understand how low temperatures can affect paint application, namely how it can change the drying pattern, characteristics and performance of the paint. Cold weather affects painting because alkyd and oil paints are based on natural oils and resins that at low temperatures become more viscous (they get thicker). So when painting in cold weather, some paints, will become very thick and require thinning. Water-based paints will freeze at low temperatures (see previous advice about Frozen Paints). Water-based paints are affected mostly by the slower evaporation rate of the water.
Cold weather will slow drying time and will extend your re-coat times. Re-coat time, using a water-based paints, at 23 degrees Celsius requires a period of approx. 4 hours. If the temperature drops to 10 degrees, then the re-coat time will be extended to approx. 6 hours. Painting in cold weather using alkyd paints will require even more time, in some instances more than 48 hours before re-coating. It is important to note that the surface temperature can vary between different areas on the same structure, causing the drying time to vary as well.
Painting in cold weather can cause issues like: film cracking, poor adhesion, improper film formation causing a weak or powdery film, lack of stain resistance, colour uniformity issues, loss of gloss or uneven sheen levels, slow drying times and the potential for staining as a result of long exposures to moisture. If you're painting onto a surface that has moisture on it, then you're going to struggle with both application and adhesion. If the surface remains damp to touch, then don't paint on it.
If you have no other choice, than painting in cold weather, here are some tips:
Verify that the paint manufacturer recommends the paint for your specific temperatures.
Pay extra careful attention to the instructions on the paint tin.
Check the surface temperature, not just the air temperature.
Paint between 10 am and 2 pm (generally the warmest part of a day).
Paint from the first dried, warmer areas in conjunction with the sun.
If painting in the late afternoon, care must be taken to avoid evening dew/condensation.
Where possible shield from cold winds or heat the areas/surfaces prior to painting.
If required, always dry the surface before painting.
Paints with high quality resins (like FLAG products) perform better than cheap ones!