The Blue Mountains is a mountainous region and a mountain range located west of Sydney in New South Wales, Australia.
The Blue Mountains Range comprises a range of mountains , plateaux and escarpments extending off the Great Dividing Range about 4.8 kilometres (3.0 mi) northwest of Wolgan Gap in a generally south easternly direction for about 96 kilometres (60 mi), terminating at Emu Plains . For about two thirds of its length it is traversed by the Great Western Highway and the Main Western railway line . Several established towns are situated on its heights, including Katoomba , Blackheath , Mount Victoria , and Springwood . The range forms the watershed between Coxs River to the south and the Grose and Wolgan rivers to the north. The range contains the Explorer Range and the Bell Range.
The Blue Mountains are a dissected plateau carved in sandstone bedrock They are now a series of ridge lines separated by gorges up to 760 metres (2,490 ft) deep. The highest point in the Blue Mountains, as it is now defined, is an unnamed point with an elevation of 1,189 m (3,901 ft) AHD , located 7 kilometres (4.3 mi) north-east of Lithgow.
The climate varies with elevation. At Katoomba, (1,010 m or 3,314 ft) the summer average maximum temperature is around 22 °C with a few days extending into the 30s (80s–90s °F) although it is quite common to see maximum temperatures stay in the teens when east coast troughs persist. Night-time temperatures are usually in the teens but can drop to single figures at times. During winter, the temperature is typically around 10 to 11 °C in the daytime with −1 °C or so on clear nights and 3 to 4 °C on cloudy nights. Very occasionally it will get down to -3C or slightly lower but usually the coldest air drains into the valleys during calm, clear nights. The Blue Mountains is not known for particularly cold mornings compared to other areas on the Central Tablelands like Oberon, Bathurst and Orange etc. There are two to three snowfalls per year although settled snow has become less common in recent decades. In the lower mountains, however, the climate is significantly warmer.