The Bureau of Meteorology is forecasting temperatures in the high-30s to low-40s for much of NSW on Thursday amid strong north-westerly winds. Sydney is predicted to hit a high of 41, with the chance of a thunderstorm in the afternoon and evening as well as gusty winds. Even the Bondi area, which is usually a few degrees colder due to coastal winds, is tipped to reach 39 degrees. Elevated fire danger is set to return on Thursday amid high temperatures. Credit:Kate Geraghty Fire weather is looking particularly dangerous in the Blue Mountains, where 45-60km/h winds are forecast with gusts in elevated areas potentially surpassing 90km/h. A weak southerly change won't hit Sydney until early on Friday morning, dropping temperatures and bringing possible showers – but temperatures on Friday and the weekend will remain above the average (26) for January.

Sydney will return to sweltering temperatures on Thursday, with a top of 40 in the city. Credit:Renee Nowytarger Nowra, near the Currowan fire that has devastated much of the Shoalhaven region, is also forecast to hit 40 on Thursday. Bowral, in the Southern Highlands, with fires burning to its north and south, is forecast to reach 35. With more than 60 fires still burning across NSW, RFS spokesman Ben Shepherd said Thursday will be another "testing day" for firefighters and communities close to the danger. Parts of NSW could experience extreme fire danger ratings on Thursday as a burst of hot and windy weather affects the state. Credit:Weatherzone Recent heavy rainfall across parts of the state "was most welcome but it might give people a false sense of security", he said.

While isolated areas received a large volume of rain during wild thunderstorms earlier this week, many firegrounds – including in the Southern Highlands and far south coast, only received 10-15mm, Mr Shepherd said. While that "did take the sting out of current fire activity", it was not enough to significantly impact the fire danger. Loading "By no means are [the fires] all out, and it is likely over coming days that we will see fires burn and move again," he said. Isolated heavy rain accompanying thunderstorms on Thursday evening may also contribute to increasingly dangerous conditions across NSW firegrounds, with loosened soil in fire-damaged areas potentially causing landslips and falling trees.