After today's record breaking early spring heat, a cool change is about to drop temperatures by 10 degrees in southwestern parts of Western Australia. Perth exceeded 30 degrees today making it the earliest day in spring to exceed 30 in 119 years of records. The previous earliest day was September 12th in 1939 when it reached 30.6 degrees. Warm northerly winds ahead of a trough filtered in heat from Central Australia producing the unseasonably early warmth, allowing Perth to exceed 31 degrees. This trough is set to move through Perth tomorrow morning bringing a showery and significantly cooler change. A 10 degree drop is expected tomorrow as showers, cloud and a cooler airmass prevent warming past the low 20s. Showery days are set to continue until the weekend as a series of cold fronts sweep across the southwest of the state. Saturday will be the coldest day barely reaching the mid teens, just half the temperature being experienced today. A ridge of high pressure will bring more stable conditions from Sunday allowing days to gradually warm up, although mornings will be noticeably cool to start the week.