The heatwave "setting in" across most of the NT and including Katherine is most unusual for February.
That was the only admission from the Bureau of Meteorology today that average weather conditions continue to elude Katherine and many other areas.
With a record of 39 degrees, Katherine's maximum is expected to blow past that to 41 in the next few days.
It comes as a time of grave concern about the poor wet season in Katherine which has failed to produce the usual "flushes" in the Katherine River.
Many long-term residents consider it highly unusual the hot springs is still accessible in February, supposedly the wettest month of the local wet.
The bureau today said the heatwave has already taken hold in central NT and Arnhem and Carpentaria regions and from Thursday it was forecast to expand its footprint to the Top End and intensify its severity to extreme heat in some areas.
"It is unusual to have a heatwave this widespread and intense at this time of year, creating potential for some temperature records to be broken," a bureau spokeswoman said.
More reading:Wet season has been a fizzer for Katherine.
Over 40C temperatures are being forecast later this week for many locations from Katherine to the southern border, including Tennant Creek and Alice Springs.
"The heat wave is being caused by a ridge of high pressure that lingers as no favourable weather systems present themselves to move it along.
"Before the heatwave creeps into Darwin and the Daly region on Thursday severe thunderstorms are possible across the Top End.
"Showers from thunderstorms will become less likely in the eastern Top End as the week progresses, while in Darwin and the rest of the western Top End a moderate chance of showers will continue.
"A trough over central Australia is forecast to cause isolated showers and thunderstorms."
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