Two men who hiked for miles through northern California wildfire territory expecting a grim discovery were met with a joyful one instead.

Jack Weaver and his brother-in-law Patrick Widen walked around police barricades, through a creek and up treacherous hilly roads to save Mr Weaver's mother from having to recover the body of the family's beloved dog Izzy.

Katherine Weaver was convinced Izzy died in a ferocious wildfire that destroyed their neighbourhood and sent the family fleeing for safety.

When the men reached the end of the narrow road, and had all but given up hope, Izzy came bounding out of the rubble.

Jack Weaver, who was filming the scene for his parents, captured the joyous reunion on his phone in a video that's gone viral, providing a rare bit of good news amid endless scenes of severe destruction.