On Saturday, Perth is on target for its hottest day since Boxing Day 2007, but it could be even hotter. Temperatures soared at the start of this week to 39 degrees on Monday before a cool change brought relief. The heat is now pushing back into the western capital with Saturday set to reach into the mid-40's. Perth has only reached 40 degrees once this summer, during the mid-December heat wave. It is very likely to go further into the 40's on Saturday as a very hot airmass moves into the area. Many residents will remember the last time Perth was similarly hot, when it reached 44.2 degrees on Boxing Day in 2007. A new record is not out of the question. The hottest temperature recorded in Perth was 46.2 degrees in 1991 at the Regional Office. If the Freemantle Doctor is very weak or fails to reach the city altogether then this kind of temperature is a chance. Even if it fails to break the record, this kind of heat will still put a halt to regular weekend plans with most people wisely staying indoors and drinking plenty of water. That night will be quite uncomfortable, mostly lingering near 30 degrees before falling to about 27 early on Sunday morning. Sunday will heat up quickly and possibly nudge 40 degrees before a cool change arrives, limiting the heating and bringing relief from the scorching heat. Thankfully it should be quite a while before temperatures soar to these heights again in Perth.