THE mercury is set to climb up to six degrees above average this week as Warwick swelters through a heatwave.

Bureau of Meteorology forecaster Janine Yuasa said the low-intensity heatwave would see the city hit maximum temperatures of 36 degrees today, tomorrow and Wednesday.

Residents already sweltered through a 34-degree day on Sunday.

Ms Yuasa said the average temperature for this time of year was 30.1 degrees.

"We are currently under the influence of a ridge of high pressure at the surface and upper levels of the atmosphere,” she said.

"When that happens we get a lot of subsiding air and that air warms as it sinks towards the surface.”

The temperatures will climb particularly high over the next two days as the wind changes from north-easterly and instead blows in more hot air from inland.

"We do see the winds turn a bit more towards the west and that will bring across that heat from the interior,” Ms Yuasa said.

Heatwaves are hitting much of Queensland and northern New South Wales, with three or more days of unusually high maximum and minimum temperatures.

Residents started flocking to the pool at WIRAC when the temperatures first started to climb last month and lifeguard and personal trainer Sophie Amos said it had been busy ever since.

"As soon as the first heatwave came through (last month) everybody decided they wanted to come in,” she said.

"The heat is definitely bringing people in, which is good to see a lot of people in the pool.”

Ms Amos said regulars continued to go in for their daily exercise, but entire families had also jumped into the water in recent weeks.

"It's nice to see people bringing their family out rather than sitting at home,” she said.

"Jumping from pool to pool and running backwards in the rapid river, it's wonderful. They're having lots of fun.”

Ms Yuasa said there was a chance of a storm on the Granite Belt tomorrow and Thursday.

Warwick is on the edge of the activity but Ms Yuasa said the city could still experience some relief from the heat with some rainfall.

But temperatures are expected to remain high, with Thursday and Friday both expected to reach 33 degrees with a top of 36 degrees on Saturday.

"It could return (to average) over the weekend or early next week but this far out it's uncertain what's going to happen so keep an eye on the forecast,” Ms Yuasa said.