Even When Left Out At Room Temperature, Butter can be Good For Several Weeks.
In spite of the fact that it is made from milk, butter can be stored at room temperature. According to research conducted in Korea, butter can be stored at room temperature for weeks or even months without going rancid. Because it contains a high percentage of fat, butter, and salted butter in particular, poses a low threat of bacterial growth.
The USDA states that butter can be stored at room temperature, despite the fact that doing so may cause it to become rancid. Butter can be kept on the counter for several weeks in an airtight container if the temperature is maintained at or below 70 degrees Fahrenheit.