If you are writing a retrospective piece or a blog post about life during that specific month:

This is a popular social riding club for women that was highly active in 2010.

: "By July 2010, the digital landscape was shifting; 40-something women were becoming the fastest-growing demographic on Facebook, trading traditional puzzles for social games and redefining how their generation connected online." 4. "40 Something Cowgirls"

Can a relatively low-intensity intervention by health ... - Nature

: "July 2010 marked a summer of grit and grace for the 40 Something Cowgirls. From local chapter meetups to high-point competitions, it was a month dedicated to sisterhood, the spirit of the West, and the courage to ride tall at any age."

During this time, the term was also used in media to describe the "40-something" demographic's shift toward digital trends.