Mt. Isa’s climate can be described at tropical-continental, with three seasons; a mild season with low humidity (May to August), a hot season with low humidity (September to December), and a hot, humid season (January to April). Temperatures can get HOT, and rainfall varies from year to year. December to March sees thunderstorms, and occasionally cyclones, that can cause flooding on the river.
Mt. Isa gets very busy during the Rodeo in August, so if you are not attending this event it would be better to visit at another time.