One thing you won't need on Monday if you live in mainland Australia is an umbrella - unless it doubles as a parasol.

The Bureau of Meteorology had forecast Australia to be all but rainless for the day - aside from a tiny splotch off the Kimberley and western Tasmania.

The unusual reading, especially for the mainland of roughly 7.6 million square kilometres, had the agency's boffins poring over their record books.

"The team can't comprehensively identify a day in our records where there hasn't been rain somewhere on continental Australia," a bureau spokesman said.