The dollar index fell 1.15 percent on Friday against a basket of six currencies.
The U.S. currency's decline was also due to the strength of the yen, after the Bank of Japan underwhelmed investors by expanding monetary stimulus through only a modest increase in purchases of exchange-traded funds, to try and spur growth and accelerate inflation towards its 2 percent target.
Spot palladium rose 2.23 percent to $711 an ounce, getting close to Thursday's peak, which was its highest since October 2015. It is up 18 percent this month, and on track to notch up its best monthly performance since February 2008.
Spot platinum climbed 1.73 percent to $1,147 an ounce and was on track for its best month since January 2012, with more than 10 percent growth this month. It hit a 14-month high on Wednesday.
"We are bullish on the PGMs (platinum group metals) fundamentally, but we are unclear as to whether or not fundamental motivations have been driving the current PGM rally," HSBC said in a note.
Spot silver was up 0.71 percent at $20.29 an ounce, and headed for a second monthly gain.