Parts of New South Wales had their coldest October morning in almost a decade, although the week will end on a warmer note. A large high pressure system caused light winds and clear skies overnight, providing the ideal conditions for a cold morning. Armidale Airport dipped to a low of minus two degrees, which is the coldest October morning in nine years. Scone and Cessnock both reached a low of two degrees, the coldest mornings for October since 2008 and 2009 respectively. Parts of Sydney also felt the cold this morning. Richmond cooled to five degrees, the coldest October morning in two years. The low temperatures also allowed fog to develop in parts of the state, including the South Coast, Illawarra and Sydney basin. Thick fog reduced visibility to just 100 metres in Campbelltown and 150 metres in Armidale. Despite the cold morning, New South Wales will experience warm days this week. Skies will remain mostly clear under the high pressure system, bathing the state in sunshine. Warm northerly winds will then draw heat in from the nation's interior, sending temperatures soaring. Western towns such as Bourke are likely to reach 30 degrees today, with temperatures reaching the mid-20s near the coast. Thursday will be even hotter, hitting the high 20s in Sydney, Newcastle and Dubbo. By Friday, many centres will reach 30 degrees, including Sydney. A cool change will bring an end to the spring heat by the weekend. Cloud and possible showers will keep the temperature below about 22 degrees for most of the weekend in Sydney.