Queenslanders have been warned to watch out for crocodiles in the wake of "incredible" rainfall from ex-tropical Cyclone Owen.

The system has been downgraded to a tropical low, but there is a low chance it could re-form later off the state's east coast.

Premier Annastacia Palaszczuk said large reptiles had been spotted in the floodwaters and urged people to take precautions.

"There are a lot of crocodiles that are being sighted at the moment so be careful on the roads and please don't go near the crocodiles," Premier Palaszczuk said

Police conformed at least one crocodile was spotted close to a woman who was rescued from floodwater on Saturday night.

Cyclone Owen weakened as it passed near the Gulf of Carpentaria, and on Sunday morning was about 80km offshore near Cooktown.

There a low chance it will re-form into a tropical cyclone in the Coral Sea on Tuesday, according to the Bureau of Meteorology.

The bureau said the heaviest falls were at Halifax, east of Ingham, which recorded 681mm of rainfall. Also, wind gusts up to 100kmh were recorded at Lucinda.

Flash flooding is expected to remain a threat with more than a dozen roads closed to traffic including the Bruce Highway between Ingham and Cardwell and also between Townsville and Ingham.

The bureau has issued flood warnings for the Herbert and Bohle rivers and is closely monitoring the Horton, Don and Pioneer rivers in Far North Queensland.

A second front of severe weather is moving through southeast Queensland.

The Bureau of Meteorology has issued has issued thunderstorm warnings for both north Queensland's central coast and the southeast corner as slow moving cells produce heavy rain.

Residents are urged to follow emergency service advice until the system dissipates.