During the SXSWGaming event, Aaron Webber officially confirmed the release date of Sonic Boom: Fire & Ice on 3DS.
Webber revealed that the game would be hitting store shelves on September 27th. It wasn’t clarified (to my knowledge, no archive exists at the moment to recheck) if the date was specifically for NA, EU, or both. But seeings as the SXSW panel was hosted in the US, we’re assuming this is a North American release date for now.
We’ll update once we know for sure about the specific region of the date, though.