This song popped into my head this evening:
It's "Cool for the Summer" by Demi Lovato. The song was common for a time on the radio a year ago but it seemed to disappear once it came off the charts, which was unfortunate. "Cool for the Summer" is a single from Confident, Lovato fifth studio album.
I have written about Lovato before; she appeared in this post of mine from July 2014, in which I discussed her collaboration with The Vamps. I suspect "Cool for the Summer" came to me today because it's hot and a cool down is needed!