Lingering ex-cyclone Oma won't transform back into a full-blown weather fiasco but will still cause hazardous surf conditions in the coming days, forecasters say.

The weather bureau's latest advice came as four riderless surfboards washed up on Gold Coast beaches, sparking a brief but urgent search for potential missing riders, with the help of police.

"This did raise some concerns that there were still people out in the water," a Surf Life Saving Queensland spokesman said from Kirra beach.

"If you do lose a board, can you please go up to the nearest lifesaver or lifeguard and let them know."