"What we're seeing here this morning for the dollar is largely a risk-off safe haven bid," said Erik Bregar, head of FX strategy at Exchange Bank of Canada in Toronto, adding that the trigger was in the European morning on rising fears of a new U.K. nationwide lockdown.
"It's scary stuff that reminds you of March," he said.
The dollar - subdued during Asian hours - perked up in London trade as European stocks sank to two-week lows and U.S. stock futures fell.
The index that measures the greenback against a basket of peer currencies was last up 0.64% at 93.555.
The greenback also managed to bounce back from a six-month low to turn flat against Japan's yen, which last traded at 104.56 against the dollar after earlier hitting 104.00, which was its lowest point since March 12.
"If it takes out the 104 level vis-à-vis the dollar, it (yen) can really take off and then all eyes are going to be on the Bank of Japan because they wouldn't like it one bit," said Exchange Bank of Canada's Bregar.
Marshall Gittler, head of research at BDSwiss, said the yen's rise was part of a typical "risk-off" move in FX markets with the exception of the Swiss franc, which turned weaker. CHF=
"With the pickup in foreign bond yields for Japanese investors getting less and less, capital flows out of Japan may fall even further," he said.
Key for the U.S. currency's direction this week will be a slew of Federal Reserve speakers, who may shed light on the U.S. central bank's new approach to inflation.
Fed Chairman Jerome Powell is due to appear before Congressional committees, while Fed committee members Lael Brainard, Charles Evans, Raphael Bostic, James Bullard, Mary Daly and John Williams are also making public speeches.
"If Jerome Powell and the rest of the Fed speakers don't really add more meat to the Fed plans for how it's going to reach an average 2% inflation I could see the U.S. dollar trading even higher this week," said Bregar at Exchange Bank of Canada.
The euro traded 0.8% lower than the dollar at $1.1743. Sterling also fell 0.9% to trade at $1.28 as the dollar gained steam.
The Australian dollar traded down 1.2% against the greenback at US$0.7204, while the New Zealand dollar was down 1.5% at $0.6658.
(Additional reporting by Gertrude Chavez-Dreyfuss in New York, Ritvik Carvalho in London and Tom Westbrook in Singapore; Editing by Angus MacSwan, Alison Williams and Bernadette Baum) ((email@example.com; +1 (646) 223 6186; Reuters Messaging: firstname.lastname@example.org))