Oil prices slid after staging their biggest two-day rally in six years last week, on renewed worries over excess supply and China's slowing economy.
After a quiet period on the economic data front, investors are turning their attentions to this week's Canadian data including second quarter growth data on Tuesday, trade balance figures for July on Thursday, and job numbers for August from both sides of the border on Friday.
At 9:30 a.m. EDT (1330 GMT), the Canadian dollar was trading at C$1.3291 to the greenback, or 75.24 US cents, softer than the Bank of Canada's official close of C$1.3215, or 75.67 US cents on Friday.
The currency's strongest level of the session was C$1.32, while its weakest level was C$1.3303.
On the data front, Canada's current account deficit narrowed slightly in the second quarter of 2015 to C$17.40 billion, but was greater than the C$16.90 billion shortfall predicted by analysts.
US crude prices were down 0.91 percent to $44.81, while Brent crude lost 1.72 percent to $49.19.
Canadian government bond prices were higher across the maturity curve, with the two-year price up 1.5 Canadian cents to yield 0.409 percent and the benchmark 10-year rising 29 Canadian cents to yield 1.411 percent.
The Canada-US two-year bond spread narrowed to -30.5 basis points, while the 10-year spread narrowed to -73.3 basis points.