The Canadian dollar has rallied nearly 7 percent this year, helped by a broadly weaker US dollar and upbeat domestic economic data that prompted the Bank of Canada to raise interest rates for the first time in seven years last month. The central bank is expected to raise rates again this fall.

At 9:21 a.m. ET (1321 GMT), the Canadian dollar was trading at C$1.2536 to the greenback, or 79.77 US cents, up 0.1 percent.

The currency's strongest level of the session was C$1.2520, while its weakest was C$1.2561.

With little domestic news to steer direction until next week's key quarterly GDP report, the Canadian dollar will take direction from external drivers, in particular the annual Jackson Hole, Wyoming, meeting this week.

Speeches by US Federal Reserve Chair Janet Yellen and European Central Bank chief Mario Draghi will be parsed for clues on monetary policy direction, even as significant new policy signals were seen as unlikely.

Canadian government bond prices were lower across the maturity curve, with the two-year price down 1 Canadian cent to yield 1.266 percent and the benchmark 10-year  falling 9 Canadian cents to yield 1.892 percent.

The Canada-US two-year bond spread was -6.4 basis points, while the 10-year spread was -29.5 basis points.