The path of the Gulf Stream is constantly changing downstream of Cape Hatteras. The Stream often develops wave-like patterns called meanders. One meander would be a section of the Stream from one "wave" crest to the next "wave" crest.

Upstream of Cape Hatteras the meanders are constrained by the continental shelf and rarely exceed 55 km in amplitude. Once the Stream separates from the Coast at Cape Hatteras however, the fluctuations can grow to 400 km in amplitude. The average amplitude for Gulf Stream meanders is about 200 km and the average wavelength of a meander is 330 km. Like a wave progressing down a string, meanders propagate down the Stream at an average rate of 8 km/day. This velocity is separate from the current velocity of 1.5 m/s at the surface.
Due to the development and propagation of meanders, the Stream's path can be quite different from month to month and certainly from year to year. For example, in the image above the Gulf Stream follows a relatively straight path once it leaves Cape Hatteras. Only one large meander is seen in the image on the eastern side of the image. The image to the left depicts the Gulf Stream for a different year. On this image several high amplitude meanders are present and the Stream's path is certainly not straight.
Monthly variability in the Gulf Stream's path can be large, as evident from these three images which are each separated by four months. With the advent of satellite oceanography the Gulf Stream's path can be monitored daily and the development and propagation of all Gulf Stream meanders can be observed.