I live in farily hot summers and mild winters. But overall, I think seeds can be sown anytime for the coming season if you can provide the right conditions for keeping them safe until the Growing Season.
I am currently sprouting Bhut & Bih seeds for next spring. I plan to keep them inside in 3" cups as long as possible during winter, and strenthen the leaf, stem, and root systems during that time with organic fertilizers. Organic is for the soil, not the plant, so things in the plant happen slower and more naturaly, which is good during a fairly long stretch of time when you don't have room for large plants. By the window, and surrounded by relective foil, the leaves should get nice and fat, and stems short and stout.
Temperature should be warm enough for plants, since its warm enough for me. I keep temp between 66-68 during winter (yes, what a whimp, lol).
BTW, there are times to pull the seedlings away from the window, or open the window for air, depending on the weather. If you cannot open the window, I like to shake the tray or hit seedlings with a fan to toughen up their stems. I like to keep stems short as long as possible to build thickness. OY, some of my tomatoes are taller than me. There will be plenty of time for getting tall plants once Spring comes. A good solid foundation early will provide huge rewards later.