Castle Hill could yet surpass it’s hottest day ever recorded, with 44.6 the temperature at the North Parramatta weather station.
The hottest day on record at the weather station, which is the oldest continually running station to Castle Hill, was 44.8 on January 1, 2006.
Sydney has recorded its hottest temperature ever, with the mercury currently at 45.8 at Observatory Hill, at 2.55pm.
The previous record was 45.3 in January 1939.
At Sydney Airport the temperature was recorded at 46.4 at 2.32pm.
Although Australia usually experiences hot summers, Bureau of Meteorology scientists have said the current heat is not typical.
‘‘Australia has started 2013 with a record-breaking heat wave that has lasted more than two weeks across many parts of the country,’’ a joint article by meteorologists for the academic website The conversations says.
‘‘Temperatures have regularly gone above 48°C, with the highest recorded maximum of 49.6°C at Moomba in South Australia.
‘‘The extreme conditions have been associated with a delayed onset of the Australian monsoon, and slow moving weather systems over the continent.
‘‘Australia has always experienced heat waves, and they are a normal part of most summers. However, the current event affecting much of inland Australia has definitely not been typical
‘‘The most significant thing about the recent heat has been its coverage across the continent, and its persistence.’’
The bureau meteorologists said the Australian-averaged maximum daily temperature was one of the best ways to gauge just how hot the weather had been.
On Monday and Tuesday last week that temperature rose above 40°C.
Monday’s temperature of 40.33 set a new record, beating the previous highest Australian daily maximum of 40.17 set in 1972.
Tuesday’s temperature came in as the 3rd highest on record at 40.11.
The same article said the heat wave could be attributed to climate change.
‘‘As the climate system warms due to increasing greenhouse gases, more energy is retained in the lower atmosphere. That extra energy influences all our weather and climate,’’ the scientists state.
‘‘In essence, every weather system and ocean current operates in a climate system that is now, on average, a degree warmer than a century ago.
‘‘In this way, the impact of global warming is clearly observed in a distribution shift of daily weather, as well as shifts in monthly and seasonal climate, to higher temperatures. As is now communicated by many climate scientists, the warming planet is loading the climate dice in favour of warmer conditions.’’