In his ****** TOH article on installing a bathroom exhaust fan, Tom Silva describes how to vent the fan outside under the soffit. But Tim Carter at strongly recommends venting up through the roof, and warns against potential moisture problems from venting under the soffit in any climate (moist exhaust can seep back into the attic and condense).

In my situation here in Minnesota, it would be easier to vent under the soffit. Should I be concerned about creating a moisture problem with this approach, or not?