Hurricane Sandy is seen moving up towards the east coast of the US in this Nasa handout satellite image taken on October 27. Reuters/NOAA/NASA/GOES/Handout

Tropical cyclone Sandy revved back up to hurricane strength on Saturday as it churned toward the US northeast coast where it threatens to become one of the worst storms in decades.

The late-season storm has been dubbed "Frankenstorm" by some weather watchers because it will combine elements of a tropical cyclone and a winter storm and is forecast to reach the US coast close to Halloween.