This occurs, (for example), in highway maintenance when roadside brush cutting crews pile their chips at the shoulder areas. I have witnessed this along multi-mile stretches in MD or VA, with multiple smoldering brush fires from different chips piles. They're not hard to control, but do get response from local FD. Also cause rubber-necking backups. (No surprise there).
It's not normal; conditions have to be just right. But, it's a good reason to try not to do brush cutting in hot summer wx.