The Fiji Meteorological Service says the two tropical cyclones that are currently in the Pacific have intensified.
Senior Forecaster, Ian Shepherd, says Cyclone Olaf currently lies less than 800 kilometres north-west of Samoa.
He says it's a slow-moving system which is expected to affect Samoa within one or two days.
Mr Shepherd says the second system, Cyclone Nancy, is to the west of the northern Cook Islands and is expected to move south-east over the next few days and hit the southern Cooks.
"Tropical Cyclone Nancy, which is near the northern Cooks, has started to drift slowly southwards. Both Tropical Cyclones have intensified and they are getting close to Hurricane Force and they are both very serious threats to any island they bump into."
Mr Shepherd says Nancy could hit Palmerston in the Cook Islands by late tomorrow.