Sydney's hot temperatures won't last as a cool southerly change will blast through this evening. The city quickly climbed to 30 degrees under the stunning blue skies before the sea breeze arrived and moderated the temperature. Those in western suburbs have endured far warmer temperatures today as Penrith made it to 38 degrees. This afternoon cloud has increased and will stop most of the heat escaping Sydney during the early evening. However, relief is on its way as a strong southerly change is surging north along the coast. This afternoon it was located near the Victorian border, but it will reach Sydney between 9 and 11pm. The temperature will plummet and winds will be fresh, gusting to 50-70km/h particularly with the change. Tomorrow Sydney will be far cooler than today with Penrith expected to be 12 degrees cooler with a top of 25 degrees. There will also be a few showers about, mostly in the east. The showers will clear by Tuesday with the temperature rising towards Thursday. On Thursday morning skies should be mostly clear, allowing the mercury to surge into the 30's again. The city is also expected to reach the 30's as the sea breeze is unlikely to reach Observatory Hill. Cloud will then increase before a strong and cool southerly change arrives during the afternoon, dropping temperatures and bringing the risk of showers and a small risk of a storm. From Friday and into next weekend it will then be cooler again ahead of a potentially warm Christmas day.