Forecasters say a tropical cyclone is moving towards the southern Tokelaus, the second in the area in as many weeks.
The storm is moving south east towards Nukunonu, Fakaofo and Atafu.
Winds in Nukunonu and Fakaofo are expected to reach up to 140 kilometres an hour within the next 12 hours.
The cyclone is expected to cause damaging gale-force winds and sea flooding.
The Wellington-based administrator of Tokelau, Neil Walter, is in the central atoll of Nukunonu, this morning, to attend a parliamentary session, or fono.
Mr Walter says there are strong winds there at the moment but people are prepared.
"People are going through the normal preparations, they've had a lot of experience at this, including recently, with Cyclone Olaf; battening down the hatches, removing branches from trees that might cause problems, and generally going through the normal emergency routine."
We're getting strong winds up here and the sea is cutting up quite rough, but it's not clear that it will have any direct impact beyond that. It's rated as a medium-strength cyclone, at this point.
Cyclone Percy is forecast to move towards Swains Island in the northern part of American Samoa.