At 0635 AEST on Monday, the Australian dollar value of 80.58 U.S. cents, down from 81.00 US cents on Friday.
Reduced expectations for further U.S. Federal Reserve interest rates rise helped this year to surprise the US dollar to the lowest in more than two-and-a-half years on Friday, with the stubbornly weak inflation continues to be Fed policy.
New York Fed President William Dudley will not repeat a statement three weeks ago that he expected to increase interest rates once more this year, in a speech on Thursday, and to urge an agreement in the Congress, the US debt ceiling until December, both of which hit the greenback.
Concerns about the upcoming short-term effects of hurricane Irma on the US economy also weighed, analysts said.
Against a basket of other major currencies, the US dollar index fell 0.38 percent after touching a low of 91.011, its weakest since January 2015. The Aussie dollar is also lower against the yen and the euro.
CURRENCY SNAPSHOT AT 0635 AEST ON MONDAY
An Australian dollar buys:
* 80.58 U.S. cents, 81.00 on Friday
* 87.17 Japanese yen from 87.23 yen
* 67.04 euro cents, from 67.15 euro cents
(*Currency closes taken at 1700 AEST previous local session)