Here is a great graphic from the BNZ showing how the NZ dollar performed in September. You could say that it strengthened on the back of notably QE3 from the US Fed and the improving global growth sentiment. Furthermore the NZ economy has performed well under trying circumstances.
June quarter GDP accounts revealed the NZ economy finished Q2 1.6% bigger than where it began the year. That is solid economic growth under ordinary circumstances. But given the ongoing challenging and uncertain global economic environment we should not under sell this achievement. It is the strongest six month expansion we have seen in the past five years. Source: BNZ