As you start to bump up the thermostat and bring out the flannel sheets, take a walk around your home and make sure everything is ready for freezing temperatures. A few minutes now can save a lot of time later!
Latex paint is very sensitive to freezing temperatures. Even being left in a van overnight might be enough to permanently damage it. If your paint has frozen previously, it may change in consistency. If the paint looks or smells bad, it is certainly not okay to use. But frozen paint that looks good might not perform correctly. Your best bet (besides protecting your paint!) is to get fresh paint. To dispose of ruined paint, see our suggestions here.