According to the USDA, discard raw meat if it spends more than two hours above 40 degrees Fahrenheit. Even short exposures to room temperature can cause bacterial growth, so refrigerate meat promptly.
In the case of a power outage, a refrigerator can hold food at safe temperatures for up to four hours, provided the door is kept closed. After four hours, however, the food inside may enter the danger zone and begin to spoil. Not all spoiled meat is readily identifiable by appearance and smell, so if there are any doubts about how long a particular piece of meat has been unrefrigerated, discard it.