The expression "raining cats and dogs" is a common idiom used to describe heavy rainfall. However, there are several antonyms for this phrase. One of them is "clear skies," which means that the weather is sunny, bright and cloudless. Another antonym for "raining cats and dogs" can be "drought;" a period of long dry weather with no rain. Other antonyms can include "dry spell," "heat wave," and "scorching sun." All these terms signify the complete opposite of heavy rainfall, which is usually associated with floods, wet conditions, and general coldness. Therefore, depending on the context, the opposite terms serve perfectly to convey the opposite meaning of "raining cats and dogs.