If you're one of those who have already planted your tender vegetables, let me give you a few tips.
Be prepared to cover on these chilly nights. When I'd say cover, I mean one of the best ways to protect your tender vegetables such as tomatoes, peppers, eggplants, etc., would be to use something called a frost blanket, or a row cover. Some of these products are made with remedy, which is a spun-bonded material, very lightweight, and it could be laid over the top of your vegetables, offering some protection from cold and wind. My experience is that these frost covers come in three weights: lightweight, medium weight, and heavyweight.
The lightweight ones do a very good job if you're protecting from insects, and we'll keep things a little bit warmer than the outside temperature. The medium weight is probably the best one to use when trying to hold temperatures above freezing will keep your plants a little bit warmer than the lightweight. The heavyweight, I would say to use when you're expecting very cold temperatures. And once that is applied, that heavyweight cover does tend to push down on top of your plants.
You could also go to something a little more sophisticated, like a wall of water. This is simply a plastic cover that you put around your plants, and it has a baffle in it that you can fill with water. The idea is that the water will warm up during the daytime, and then it will be there to protect your plants from cold temperatures at night.