The kiwi fell to 85.63 US cents at 5pm in Wellington from 86.73 cents at the close of trading in March. It was up from 85.45 cents at 8am and 85.25 cents on Tuesday.
The trade-weighted index increased to 79.68 from 79.33 on Tuesday, and is heading for a monthly decline of 1.5 per cent.
Rising tensions between Western nations and Russia over Ukraine have kept investors on edge this month.
Traders will also be watching the outcome of the Federal Open Market Committee’s policy review on Wednesday in Washington, with the Fed expected to trim back money printing further.
“May is a pretty bad month for the kiwi, but it’s not going anywhere fast,” said Tim Kelleher, head of institutional FX sales NZ at ASB Institutional in Auckland.
“It’s quite surprising how quiet it is today given it’s month-end, US equities are flattish for the month, and with the Fed and US data in the next couple of days.”
The kiwi rose to 87.65 yen at 5pm in Wellington from 87.36 yen on Tuesday and to 62.01 euro cents from 61.48 cents, but slipped to 92.19 Australian cents from 92.36 cents.