It's Common To Use "Not Uncommon"

[Pete]

"Not uncommon" is used (at least, by me) when something is neither common nor uncommon. For example ... it's not uncommon for me to eat sushi. I don't do it all the time, so it's not common. But I do it more often than rarely, so it's not uncommon.

Like ... it's not uncommon to see snow in Tennessee. It's common to see snow in Wisconsin, and uncommon to see snow in Florida, but it's neither common nor uncommon to see snow in Tennessee.

Bingo.

common- happens often
uncommon- rarely ever happens
not uncommon- more like a "might"