This article is from the Storms FAQ, by Chris Landsea email@example.com with numerous contributions by others.
Cape Verde-type hurricanes are those Atlantic basin tropical cyclones that
develop into tropical storms fairly close (<1000km or so) of the Cape
Verde Islands and then become hurricanes before reaching the Caribbean.
(That would be my definition, there may be others.) Typically, this may
occur in August and September, but in rare years (like 1995) there may be
some in late July and/or early October. The numbers range from none
up to around five per year - with an average of around 2.