In Colonial America, Rainy was commonly used among enslaved people of both genders. The practice of giving children names that relate to their birth — such as the day, weather, or time — is common in West Africa.

The Rainy spelling puts this name firmly in word name territory, an appealing option following the rise of Stormi. Rainey is the most popular spelling of the name, given to about 50 girls last year, with half as many called Rainy and a quarter named Rainie, the spelling used by Andie MacDowell for her now-grown daughter.