The mercury is set to soar above 40C across southern Queensland over the weekend as summer arrives with gusto in the sunshine state.

An extreme heatwave is expected to sweep through the region from Thursday - the first official day of summer - until the beginning of next week.

Birdsville and Cunnamulla are set to swelter through 43C heat, while Brisbane can expect temperatures in the mid 30s according to the Bureau of Meteorology.

Meteorologist Jeanine Yuasa said the temperatures in Brisbane would be about 5C above average for this time of year.