The warmest months are January and February, with an average air temperature range at Observatory Hill of 18.7–25.9 °C (65.7–78.6 °F) for January and 18.8–25.8 °C (65.8–78.4 °F) for February.[5] An average of 14.9 days a year have temperatures of more than 30 °C (86 °F).[5] The highest recorded maximum temperature at Observatory Hill was 45.8 °C (114.4 °F) on 18 January 2013 during a prolonged heat wave across Australia from early December 2012 to late January 2013.[6][7] In winter, temperatures are mild and rarely drop below 5 °C (41 °F) in coastal areas. The coldest month is July, with an average range of 8.0–16.3 °C (46.4–61.3 °F).[5] The lowest recorded minimum at Observatory Hill was 2.1 °C (35.8 °F) on 22 June 1932.[5]
Inland, in Sydney's western suburbs, the climate is drier and summers are significantly hotter with temperatures around 2–5 °C (4–9 °F) above Sydney's and winter lows around 2 °C (4 °F) cooler than the coastal suburbs.[8] Sydney is prone to heat waves, which have become considerably more common in recent years due to an increasing trend of global warming.[9] They usually would lead to water restrictions and a high risk of bushfires (that sometimes bring a smoky haze to the city).[10] Summer can vary between humid (due to the ocean proximity) or very dry (due to the heat from the desert).[11]
In late spring and summer, Sydney can sometimes get northwesterly winds from the Outback, which are dry and hot, making the temperatures soar above 35 °C (95 °F).[citation needed] This happens after the northwesterlies are carried entirely over the continental landmass, not picking up additional moisture from a body of water and retaining most of their heat. On these occasions, the normally temperate parts of south eastern Australia can experience the full fury of the desert climate, although only briefly, as they are often ended with a "southerly buster", which is a cold front that sweeps up from the southeast abruptly cooling the temperature by bringing thunderstorms and gale winds.[12][13][14]