Sydney, Canberra and Melbourne are all set for a cold start to spring while snow could fall at Bluff Knoll in the nation's west. A broad ridge of high pressure is set to combine with a cold airmass overnight to bring a cool start across the southeast. Clear skies and light winds will allow Sydney, Canberra and Melbourne to cool well below average to kick off spring. Sydney should cool to eight degrees, while western parts of the city cool to four degrees. In the nation's capital, Canberra is set freeze overnight, cooling to minus two degrees. Further south, in Melbourne temperatures are set to cool to five degrees. This may not be what people would have in mind for the start of spring, as these minimum temperatures are all two to five degrees colder than average for September. Although temperatures will gradually warm up later in the week with warm northerlies. Heading to the west and it's a similarly chilly start as a cold front moves across the southwest. A cold day is set for Perth, forecast to be four degrees below average, while further inland rare spring snow could fall on Bluff Knoll. A few cooler days and colder starts will follow before some warmer spring-like weather finally arrives on Thursday.