The Summer Series was founded in 2005 by Bob Bavasi, former owner of the Everett Aqua Sox, of the Northwest League.

It is sponsored by Alaska Airlines' sister company, Horizon Air.

In 2008 the series was expanded with the addition of a third division, the "Bavasi Division", named after the series founder's father and former Brooklyn Dodger and Los Angeles Dodger General Manager Emil "Buzzie" Bavasi.

The Horizon Air Summer Series ceased after the 2013 season.

It has since been replaced by the Sierra Central/Montna Farms Summer Series (now known as just the Montna Farms Summer Series, again hosted by the Gold Sox.