It's never a good sign when they're circling above you, it's usually either a fire or the feds and neither one makes for a good day.
I can say with experience that when you have an acre of fire getting shoved on by downdrafts from a thunderstorm, you are alone for the first hour on the fire with a Type 6 engine (200 gallons of water), hand tools, most of the fire crowning, having an aircraft arrive and circling is very comforting. There is nothing like 3,000 gallons of retardant to make for an excellent day.