Warning for holidaymakers as summer warms up On your marks: summer's first heatwave has arrived. Photo: Paul Jeffers Australia is in the grip of its first heatwave of the summer with the Bureau of Meteorology warning holidaymakers to stay hydrated and to avoid prolonged exposure to the sun. The slow-moving high pressure system that brought blistering heat to Perth during the recent Ashes Test is now sending the mercury into the high 30s or low 40s across much of the continent. "Holidaymakers are urged to be mindful of the weather conditions in making their travel plans," said Alasdair Hainsworth, assistant director for weather services at the bureau. Hydrated if potentially over-exposed. Travellers can view forecasts from the bureau here and from Weatherzone here. "Fire dangers are expected to be very high to extreme across several states, and the public is urged to check these in their local area," Mr Hainsworth said. Much of NSW has high or very high fire danger ratings for Wednesday, while the rating for most regions of Victoria is high. Adelaide is expecting 38-40 degrees over the next three days, with Melbourne forecast to cop 40 on Thursday and 34 on Friday. Outlook for temperatures January-March 2014 Downtown Sydney will be spared the worst of the heat, with Friday's maximum to reach only 30. Areas to the west such as Penrith, though, will have a week of 30s or warmer conditions including 39 predicted for Friday. "If you live out west, you will be warm," said Max Gonzalez, a senior meteorologist with Weatherzone. Places such as Dubbo in central NSW may see a top of 39 on Wednesday and then 40 and 41 on Thursday and Friday. In Victoria, Mildura will see temperatures of 41-43 from Wednesday to Friday, the bureau said. Outlook for rain January-March 2014. "The main thing that's making the heat to peak is just the strengthening northerly winds ahead of a trough," Mr Gonzalez said. The fire danger will rise along with the temperatures although wind strengths are likely to be weaker than during the September and October fire period, he said. The heat alert comes as the bureau released its three-month outlooks for temperatures and rainfall for Australia. They show that the odds favour warmer and drier than normal conditions for the first three months of 2014 for most of eastern Australia. The forecast suggests the unusual warmth most of Australia has experienced in 2013 will extend well into the new year, with the country all but certain to post its hottest year in more than a century of records. Perth's run of five days above 36 degrees from Thursday to Monday was the earliest in the summer for the city in at least 71 years. Weatherzone is owned by Fairfax Media, publisher of this website.