Not set in stone, but rule of thumb in most cook books is that cold smoking takes place with outside temperatures below 90°, I smoke at lower temperatures.
Cold smoking is often used as a flavor enhancer for items such as cheese, chicken, beef jerky, pork chops, salmon, scallops, seafood, and even steak. The items are often cold smoked for just long enough to give some flavor. Some cold smoked foods are then baked, grilled, roasted, or sautéed before eating.
Smokehouse temperatures for cold smoking are typically done between 60 to 86 °F inside the smoker. Again this is just a guide from some books, but again I have smoked at lower temperatures.
In this temperature range, foods take on a smoked flavor, but remain relatively moist and uncooked. Meats should be fully cured before cold smoking. Other items can be packed in ice to keep cold while smoking.
Your best bet is to follow a recipe, or have someone who has successfully cold smoked the item you wish to smoke give you direction.
Humphrey's DownEast Beast W/BBQ Guru