South-east Queenslanders are hunkering down as the 600-kilometre wide Cyclone Oma looms offshore, twice the size of the category 4 Cyclone Debbie that smashed the north almost two years ago.

Premier Annastacia Palaszczuk warned residents from the central Queensland coast down to the NSW border against camping, boating, fishing, swimming or surfing this weekend.

Waves as high as seven metres were expected at the weekend as the tropical cyclone whipped up big swells, which combined with high tides.

Bureau of Meteorology state manager Bruce Gunn said the category 1 system was expected to continue moving south-south-west for the next 24 hours to 36 hours.