From Longman Dictionary of Contemporary Englishit rainsit rainsif it rains, drops of water fall from clouds in the sky Outside it was still raining. It’s starting to rain.rain heavily/hard It must have rained quite hard last night.it’s raining cats and dogs spoken (=it is raining very hard) → rain
Examples from the Corpus
it rains• But the next day it rains.• They have a low, vaulted ceiling and damp, grimy walls which run with water when it rains.• Water gushes through the roof when it rains.• It's such a clich, but boy, it sure seems like it rains every year.• He says the sun will only shine on him if it rains for at least a month.• If it rains, the programme will be aerobics, papiermâché mask making, craft work and painting etc.• If it rains, there will be aerobics and make up morning, followed by indoor cycling proficiency.• It is a city more in tune with outdoor recreation than cultural institutions, but it rains there. 