Contrary to popular belief, butter doesn’t have to be refrigerated. According to the Food and Drug Administration (FDA), it’s safe to leave butter on the counter if it’s been pasteurized and has enough fat and salt mixed in to inhibit bacterial growth. While whipped and reduced-fat butters should never stray far from your refrigerator door for long, a stick of salted butter can feel perfectly at home on your kitchen counter for an extended period of time.
Source: Store Butter at Room Temperature With These Butter Bells and Crocks