Darwin awoke to an unseasonal dry season shower this morning.

The chances of rain for Katherine continue to climb for tomorrow and Friday as cold air moves across northern Australia from the south.

Forecasters expect this cold air, tipped to bring a record low May temperature of 21 degrees for Katherine on Friday, will mingle with moisture-laden air coming from the Indian Ocean.

The Bureau of Meteorology yesterday said falls of up to 60mm are possible between Tennant Creek and Katherine.

More reading: Dismal wet season.

Weather experts are also looking closely at a tropical low forming south of Indonesia they expect will travel west and may even form a cyclone about the Western Australian coast from Sunday.

The tropical low is still 3000km away and experts admit a lot could happen still.

They say "conditions are favourable" but there is still only a slight chance for the low to become a tropical cyclone before the weekend.

If it does, it would be called Tropical Cyclone Imogen.

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