Antarctica New Zealand says a decision will be made Monday morning whether to send an Air Force Orion on a second attempt to evacuate an extremely ill American man from McMurdo Base.
The Orion left for Antarctica on Sunday morning, but turned back to Christchurch after an unexpected blizzard at the base made landing too dangerous.
Antarctica New Zealand says the weather forecast for Monday is not looking promising.
Its chief executive, Lou Sanson, says blizzard conditions are predicted to continue, with temperatures as low as minus 42 degrees, and winds of up to 42 knots.
But anything can happen, he says, and the Orion will be on standby until a decision is made at 5am.
Mr Sanson says the man's condition has stabilised, but doctors at McMurdo Base say he must still be taken to hospital.