Sunny Day is the lead play-by-play commentator/announcer of most of the Backyard Sports games (with notable exceptions of Backyard Baseball 2007, Backyard Basketball 2007, Sandlot Sluggers, and Rookie Rush). In every game, she is always partners with characters such as Vinnie The Gooch, Chuck Downfield, Earl Grey, Barry Dejay, and many other color commentators doing commentary throughout the games. Her voice was heard in Backyard Sports: Baseball 2015, but not herself. This also happens to Vinnie The Gooch.
Sunny Day is an African-American girl with dark brownish-red hair. She wears a blueish-purple jacket over a yellow long-sleeved t-shirt. In the old games, her hair is center-parted and she wears it in a bun. But in later games like Backyard Football 2004 or Baseball 2005, she has bangs and her hair is worn in a mullet.
- Unlike professional play-by-play announcers (with the exception of regional announcers), Sunny Day will commentate a bias for the human player. In the spectator mode for Backyard Hockey 2005, this bias is given to the 'Away' team curiously.
- Her name is a reference to Humongous Entertainment co-founder Shelley Day.