Temperatures are forecast to reach near 40°C in the western Top End this week as Darwin rounds out its hottest September in reliable records.

A severe to extreme heatwave will grip the western Top End in the coming days as southeasterly winds drive abnormally hot air into the NT’s Daly District.

Daytime maximum temperatures are forecast to reach 37 to 39°C over inland areas of the Daly District on multiple days this week. This daytime heat combined with overnight minimums in the mid-twenties will meet the criteria for an Extreme Heatwave, which is the highest category on Australia’s three-tiered heatwave scale.

Image: Heatwave outlook for the three days starting on Monday, September 30, 2024.

While Darwin will escape the worst of this week’s heat, temperatures will still reach about 35 to 36°C over the next seven days, which is about 2 to 3°c above average for this time of year.

This week’s heat is a fitting end to an exceptionally warm September in Darwin. The city’s average maximum temperature this month has been about 34.3°C. This is almost 2°C above the long-term average and the highest September maximum temperature on record at the current airport weather station, which opened in 1941.

Darwin’s old Post Office weather station, which recorded temperature from 1882 to 1942, contained two Septembers that were warmer than 2024 based in maximum temperature. These were 35.0°C 1882 and 34.4°C in 1889. However, these observations are dubious.

Temperatures recorded in the late-1800s are less reliable than those observed with modern equipment and instrument standards. For example, 7 of 12 monthly maximum temperature records in Darwin were set between 1882 and 1892, in the first 11 years of the city’s 143-year period of records.

There is a good chance that this month was Darwin’s hottest September on record.