Bushfire threat to Sydney suburb homes A large grass fire could threaten homes in Sydney's west as the temperature soars past 30 degrees, firefighters say. Strong winds catch out a RFS truck in the Castlereagh area. The NSW Rural Fire Service has issued an emergency warning as strong northerly winds carried the fire towards George Street and Bligh Park, according to the RFS website. Classes at the Hawkesbury campus of the University of Western Sydney have been disrupted with the nearby bushfire cutting power. At midday, the NSW Rural Fire Service said the fire in Castlereagh was burning towards Devlin Road, and "may impact on properties in the next 30 minutes." "It's currently an emergency warning, which is our highest level of warning," said Laura Ryan, a spokeswoman for the Rural Fire Service. The fire has burnt out about 60 hectares and had not been contained by noon. Ms Ryan said there were 11 fire trucks so far in attendance. The cause of the fire will be investigated. Another fire of concern is in Muswellbrook, near Newcastle. The blaze is about two kilometres from an Orica chemical plant. "The Orica plant has decided to evacuate their plant" following their own procedures, Ms Ryan said. "We classify that fire as low risk but there is a risk because they do store explosives at the Orica plant," she said. The RFS has warned residents in the area of the Castlereagh fire who are away from their homes that it may not be safe to return. Residents have been asked to monitor the RFS website, listen to radio broadcasts or call the NSW RFS Bush Fire Information Line on 1800 679 737. Tuesday's heat marks the second day this month of 30-plus degree weather, a record for so early in spring, said Ben Domensino, a meteorologist with Weatherzone. Just before 1.30pm, the temperature in Sydney was 31.6 degrees, passing the high of 31.1 degrees on Saturday, which was the warmest day since late March. Wind has also made fire conditions worse, with gusts reaching 67 kilometres an hour at Penrith just after midday, and 78 km/h over the harbour in the late morning. The winds should drag the smoke from the blaze into the Sydney basin. Sydney and surrounding regions have largely been dry since mid-June, contributing to an unusually high fire risk so early in the warming season. "This spring there's going to be significant fire danger," Mr Domensino said. While Sydney is unlikely to see 30-degree days for the next couple of weeks, temperatures are likely to remain above average until they switch to more normal conditions by the summer, Mr Domensio said. Rainfall should also remain below normal for most of spring, he said. Weatherzone is owned by Fairfax Media