An out of control scrub fire burning at Bridge Hill in Canterbury has grown to 450 hectares.
Nine helicopters, three planes, and 12 trucks, tankers and support vehicles are among the resources being thrown at the blaze.
Three school camps staying about a kilometre from the fireground have been evacuated as a precaution, as has Flock Hill Lodge.
State Highway 73 is closed between Castle Hill and Arthur's Pass village.
Meanwhile, Otago firefighters from multiple brigades are responding to a rash of vegetation fires in Central and Coastal Otago this afternoon, and strong winds, warm temperatures and low humidity are making some of the blazes challenging to contain.