Tomorrow's weather forecast for Far North Queensland contains an unusually rare anomaly for the tropics — the day's expected maximum and minimum temperatures are almost identical.
The Bureau of Meteorology initially predicted an identical minimum and maximum of 20 degrees for Cairns but has since updated that forecast to a 21-degree maximum.
Other locations across the north tropical coast and tablelands including Innisfail, Port Douglas, Mareeba and Atherton can all expect just a single degree of variation too.
Senior forecaster Gabriel Branescu said while he could not confirm it was unprecedented for the region it certainly was unusual.
"It's definitely an exceptional situation. It's very uncommon in the tropics," Mr Bransecu said.
A combination of climatic factors is responsible.
An upper trough will bring across a thick cloud band from the north-west while behind a surface trough pushing offshore early in the day will be a cold airmass pooling from the south-west.
"Combining with that cloudiness overtop [will be] very dry winds, south-westerly winds at the surface," Mr Branescu said.
"[That will] cause these unusual circumstances where the minimum temperatures in some places in the northern tropics might equal the maximum temperatures of the day.
"Basically, you will not see any heating occur during the day.
"We might see just point-five or one-degree [difference] but it will definitely be very close, the minimum and maximum values for Saturday."
If temperatures don't exceed 20 degrees in Cairns, that will be a new record for the tropical tourist city's coldest May day.
"The record minimum is 20.5 — that was May 26 in 1990," Mr Bransecu said.ABC