Although the canoe is a reasonably stable craft, it is definitely affected by wind and waves. A brisk headwind can turn a leisurely paddle into a grueling battle, and a tricky cross wind can mean you spend as much energy trying to keep the canoe on course as you do propelling it forward. This is a lesson Gerry and I learned last year when we left the calm waters of the Nipising River and were suprised by the pounding we took while crossing Cedar Lake.
Large swells from the side can potentially dump you into the drink. Breaking waves from the bow or stern can fill and swamp your canoe in a hurry.
Avoiding Prevailing Winds
Some local winds are caused by sunlight warming air over the land, which rises, drawing in cooler air from over lakes and other bodies of water. This cooler air also warms up over the land mass and rises. This local wind effect can sometimes be avoided by paddling early in the morning or late in the evening.
Heading into Open Water from a Lee Shore
Any time you leave the sheltered lee shore and head into a large body of water, caution is advised. Even on a windy day, the water immediately adjacent to the shoreline will always seem calm, since the land mass is blocking the winds.
As you get a little further out into the lake, the winds will begin to drop to the lake surface and cause some waves. A bit further, the sheltering effect of the land becomes non-existent and you may find yourself in huge rollers or breaking waves. At this point, it is very difficult (sometimes impossible) to turn the canoe around and head back to the shore without taking waves broadside and swamping or tipping it.
Two big thumbs-up to all of you that responded to my request for comments! It was so great to see the remarks from the people that actualy read my blog and I will do a seperate post to respond to all of your questions. 
