Australia's longest urban heatwave set to end

The longest heatwave of any Australian capital city is about to end.

Adelaide's maximum temperature will tomorrow drop below 35 degrees for the first time since March 3.

The extended heatwave surpassed the previous longest stretch of temperatures above 35 degrees recorded by Perth in 1988.

After sweltering with a 40.5 degree maximum today, Adelaide is predicted to drop to 29 degrees tomorrow and even cooler on Wednesday and Thursday.

The Bureau of Meteorology said the average maximum temperature for March so far in Adelaide was 37.2 degrees - well above the average of 26.2 degrees.

A bureau spokesman said the conditions during the past fortnight were caused by a dominance of a high pressure ridge over the eastern part of the state, which was directing a hot to very hot and dry north-easterly air stream over the state.

Total fire bans have been declared throughout the state but no major bushfires have been reported.

- AAP