Hot air wafting over southwestern Australia will send the mercury soaring in Perth on Tuesday. The city is forecast to reach a top of 38 degrees tomorrow, which is eight above average for this time of year. Tuesday's forecast high is equal to the hottest day Perth had last season, which was the city's first summer in 16 years to remain below 40 degrees. Perth will easily be the hottest capital city in Australia on Tuesday, trumping forecasts of 33 degrees in Darwin and 27 degrees in Adelaide and Melbourne. The temperature will drop back to the low thirties on Wednesday, although increased humidity from onshore winds will keep it feeling a little warmer than usual for this time of year.