After a sweltering week in the nation's southwest, a cold front will cross the region on Sunday bringing the coolest day in a month for places like Perth and Bunbury.
Tomorrow's cooler weather will come as a contrast to the past week, which included Perth's hottest five-day spell in 12 years. The coolest day between Saturday and Wednesday in the WA capital reached 37.6 degrees, making it the hottest five day run since 2001. A weak trough then brought a brief cooler change on Thursday, with the temperature rebounding to 34 degrees on Friday.
It has been a similar story for Busselton, where it was hotter than 33 degrees every day in the last week except Thursday. Tuesday was their hottest February day in three years, climbing to 37.5 degrees.
The nights have also been uncomfortably hot. In Bunbury it only cooled to 24.1 degrees on Monday and Tuesday nights, the warmest in nine years.
The hot spell has been the result of a trough remaining offshore most days, allowing inland heat to push through the region. This trough will move inland during Saturday, causing winds to tend southwesterly by early afternoon and temperatures to dive. In Perth it will reach 32 degrees ahead of this change, before dropping by about five degrees during the afternoon.
A cooler air mass will arrive early on Sunday with a stronger cold front, leading to an expected top of just 26 degrees in Perth and 25 degrees in Bunbury and Busselton. This would be the coldest day in exactly one month for these towns.
The cooler weather won't last long though, with temperatures climbing back into the mid-to-high 30s in Perth again by Wednesday.
© Weatherzone 2013
12:38 EST Tropical Cyclone Jack has rapidly developed over the warm waters of the Indian Ocean in the past 24 hours, making it the 10th system to be named this season.