Tropical Cyclone Ann is currently a category two system and is sitting about 950km east of Cairns, moving toward the coast.

Bureau of Meteorology meteorologist Michael Gray said it was unusual for a cyclone to form in May, as the official cyclone season was between November and April.

However, he said it was not unheard of.

The last tropical cyclone to form in the Coral Sea in May was Tropical Cyclone Pierre in 2007, however it did not reach the coast.

The last cyclone to cross the Queensland coast in May was in 1989, when Tropical Cyclone Meena crossed near Weipa.

Mr Gray said Cyclone Ann would weaken as it approached the coast, and was likely to cross as a low pressure system.

"Ann is currently about 950km to the east of Cairns and is moving to the west north-west at about 24km/h," Mr Gray said.

"It is expected to start weakening through this afternoon and this evening and by later tonight it will be a category one and by tomorrow it will probably be a tropical low, rather than a cyclone."

Mr Gray said heavy rainfall, with isolated falls up to 200mm could be expected from about Cooktown to Innisfail from tomorrow.

"The main impact is likely to be rainfall from about Cooktown to Innisfail, in particular Tuesday and Wednesday, we may see over 100mm south of Cairns and isolated falls of 100mm-200mm across that area.

"Rainfall is predicted right down to Mackay for the next few days."

Mr Gray said inland areas were unlikely to see rain, with the falls confined to the coast.

He said strong wind warnings were also in place for waters north of Burnett Heads.

- courtesy North Queensland Register