Strong currents and southerly winds are keeping swimmers out of the surf, Whanganui Lifeguard Service spokesman Daniel Comp says.
The swimming season started early this year, with a series of fine, hot days. It took a dive in the other direction a week and a half ago, with the advent of strong southerly winds.
Whanganui's lifeguards started their patrols on December 16. They have been at Castlecliff and Kai Iwi beach from noon to 6pm as usual for the last few days, but people have mainly been warned not to go in the water.
The currents changed with the southerly winds, and tides have been higher than usual.
"It's been really messy," Mr Comp said.