The same general food safety guidelines apply to hot dogs as to all perishable products — "Keep hot food hot and cold food cold."
When you leave the grocery store with hot dogs, head straight home and refrigerate or freeze them immediately. If there is no product date, hot dogs can be safely stored in the unopened package for 2 weeks in the refrigerator; once opened, only 1 week. For maximum quality, freeze hot dogs no longer than 1 or 2 months. And, of course, never leave hot dogs at room temperature for more than 2 hours and no more than 1 hour when the temperature goes above 90°F.
Although hot dogs are fully cooked, those at increased risk of foodborne illness should reheat hot dogs and luncheon meat until steaming hot before eating, due to the threat of listeriosis.
Source: www.fsis.usda.gov