The New Zealand dollar is at its highest in nearly three years.
The kiwi gained more than 1 cent on Thursday, prompted by reports that China is considering investing billions of dollars in the economy.
At 6.15am on Friday, the dollar was trading at 81 US cents.
Westpac economist Imre Speizer says the dominant driver has been the weakness of the greenback.
He said the kiwi is still playing catch-up with the Australian dollar, after it lagged following the Canterbury earthquakes and some weak economic data late last year.
But Mr Speizer said it is now moving up against the Australian dollar.
At 12.20pm on Friday, the New Zealand dollar was trading at 80.77 US cents, 76.12 Australian cents, 49.31 pence, 65.57 yen and 0.5716 euro. The Trade Weighted Index was at 70.10.