The Australian dollar is almost one US cent lower following sharp falls in gold and silver prices on Friday night.
At 1200 AEDT on Monday, the local unit was trading at 102.80 US cents, down from 103.64 cents on Friday.
ForexCT head of research Steven Dooley said the Australian dollar had broken with its trend of following sharemarket movements.
He said the main reason for this was the improvement in the global economy and the decreasing need for economic stimulus programs in the US like quantitative easing.
"When global equity markets went higher the Aussie dollar went higher," he said.
"We've seen that detach over the last month and a half, and it's really become most noticeable over the last week or so.
"... The Aussie dollar and gold are getting crunched, because people are downgrading expectations that we will see more quantitative easing from the United States."
Mr Dooley said currency markets were awaiting the minutes of the Reserve Bank of Australia's (RBA) February 5 board meeting, at which the cash rate was kept at three per cent. The minutes are due to be released on Tuesday.
"Domestically, of course, we're unlikely to get any action for the next 24 hours because we're all just waiting for those RBA minutes," he said.
"The last meeting we had, markets were quite surprised by the dovishness of the Reserve Bank, the way that they said the current inflation outlook means they've got scope for further cuts.
"So, there's two big things that are pushing the Aussie dollar lower."
Mr Dooley said he expected the Australian dollar to trade in a range between 102.50 US cent and 103.20 cents on Monday afternoon.
He said trading volumes were expected to be quite low because US markets will be closed on Monday for the President's Day public holiday.
Meanwhile, the Australian bond market was weaker.
At 1200 AEDT on Monday, the March 10-year bond futures contract was trading at 96.460 (implying a yield of 3.540 per cent), down from 96.500 (3.500 per cent) on Friday.
The March three-year bond futures contract was at 97.090 (2.910 per cent), down from 97.140 (2.860 per cent).