A low pressure trough will direct a hot airmass over southwestern WA on Monday with some areas reaching 11 degrees above average.

Less than two weeks ago Perth reached 30 degrees. The mercury is forecast to reach 30 once again on Monday - nearly 10 degrees above the monthly average.  If it gets hotter than 28 it will be the hottest September day since 2015 when it hit 32.1 degrees. 

Other areas that could have their hottest September day since 2015 include Dwellingup, Albany and Narrogin - all forecast to reach 28 which is more than 10 above average.

Further north, Gingin is forecast to reach 32 which would be the hottest September day since 2014 and over 11 degrees above average. 

A seabreeze should develop along the west coast during the afternoon. Although this will drop the temperature by a few degrees it will bring an increase in humidity, potentially making the heat more uncomfortable.

The early Spring heat will be short lived. Although a warm airmass will linger over the southwest from Tuesday, light winds will allow an early sea breeze to develop - keeping the mercury in check. Temperatures throughout the southwest are likely to remain above average though for much of the next though.