Sydney hits 42C before dramatic shift causes temperature in some parts of city to drop 15C in an hour

An afternoon storm rolled in to relieve some of the stifling heatwave conditions in Sydney. Photograph: Steven Markham/AAP

Sydneysiders have sweltered as temperatures soared above 42C in parts of the city before an afternoon change caused the mercury to plummet more than 15C.

Edward Townsend-Medlock, a meteorologist at the Bureau of Meteorology, said a sea breeze followed by the cool change delivered the sharp drop on Tuesday.