Marble Bar heatwave, 1923-24

The world record for the longest sequence of days above 100°Fahrenheit (or 37.8° on the Celsius scale) is held by Marble Bar in the inland Pilbara district of Western Australia. The temperature, measured under standard exposure conditions, reached or exceeded the century mark every day from 31 October 1923 to 7 April 1924, a total of 160 days.

Temperatures above 100°F are common in Marble Bar and indeed throughout a wide area of northwestern Australia. On average, Marble Bar experiences about 154 such days each year. The town is far enough inland that, during the summer months, the only mechanisms likely to prevent the air from reaching such a temperature involve a southward excursion of humid air associated with the monsoon trough, or heavy cloud, and/or rain, in the immediate area. This may sometimes be associated with a tropical cyclone or a monsoon low. In the record year of 1923-24 the monsoon trough stayed well north, and the season was notable for its lack of cyclone activity. (In fact, the entire Australian continent was untouched by tropical cyclones throughout the season, a rare event in the 20th Century). The rainfall recorded at Marble Bar during the record 160 days was just 79 mm, most of it in two heavy, short-lived storms that developed after the heat of the day. Only a further 12 mm of rain fell before the following December. Severe drought prevailed across the Western Australian tropics, and stock losses were heavy. With no rain to speak of, and minimal cloud, there was nothing to relieve day after day of extreme heat.

"Day by day maximum temperatures at Marble Bar over the period 31 October 1923 to 7 April 1924. At the peak of the heatwave - between late December and late February - many days approached or exceeded 45°C".

The highest temperature recorded during the record spell was 47.5°C on 18 January 1924. There have been higher temperatures at Marble Bar, with the highest recorded being 49.2°C, on 11 January 1905 and again on 3 January 1922. But temperatures in other Western Australian towns have been higher: in a remarkable late-season heat-wave in February 1998, Mardie recorded a maximum of 50.5°C (on the 19th) - the highest temperature in Western Australia, and the second highest ever recorded in Australia using standard instrumentation (Oodnadatta, in South Australia, recorded 50.7°C on 2 January 1960). Several other recordings above 49°C were reported in the northwest on the days preceding Mardie’s record, and at Nyang, the average maximum over the entire summer exceeded 43°C. As in 1923-24, very dry conditions accompanied the extreme heat.