It might be cold outside, but there are still a lot of places to go if you cannot or do not want to have sex in the bedroom. You might be young and still be living with your parents, or with a roommate, and the situation might be quite embarrassing if they walked in on you while you are having a good time with a hot babe or guy. It does not matter if you are a man or a woman, you are very likely to avoid these situations. Or you might have had sex in your apartment way too many times already, and you want some variety.
The place with the lowest risk is probably your car if you have one. And if you keep the heating on, you will not even feel if it is cold outside. Romantic atmosphere can also be provided if you have the right music in the radio, or on your mp3 player, so all you need is an empty parking lot, or simply a small road outside the town, and if it is really cold outside and your actions are really intense, then the vapor will even block the view if a stranger passes by anyway.
Without a car, you need to be risky. You can simply look for a not so well-lit spot on the street – possibly on a dead-end street – but you need to be extra careful, since anybody might see you even in spite of the darkness around you.
If you need to have sex outside, always keep your clothes on, and only get rid of those that are not necessary. Ideally, a man should only undo his flies, while a woman should only pull down her pants to her knees or lift up her skirt. Have fun!