Green’s Dictionary of Slang

(orig. US) excellent, first-rate.

2016		Dly Pennsylvanian 23 Mar. 🌐 If I say ‘That class is good and interesting,’ that is a pretty generic statement. If I say ‘That class is fire, fam” it’s a funny statement’.
2024		Axis Parents’ Guide to Teen Sl. 🌐 Fire = Cool, awesome. ‘This party is fire!’.