Sandy was a cat 4.
Sandy was a category 0 when it hit. That is when it counts.
Sandy was a cat 4.
What made Sandy devastating was its size (1100 mi across, the largest recorded Atlantic Hurricane) and that it was stalled in position by two high pressure systems. Even the storm surge was significantly lower than that which hit the Gulf Coast with Ike or Katrina.
However, the area was not set up for a storm of that intensity, and there was a lot of high-dollar real estate built on barrier islands. New York also has lots of infrastructure which is below ground and subject to flooding.
I'm not minimizing the effect, just saying the storm intensity was not high enough for a CAT4 (be thankful, the damage would have been far worse).
In fact, I just read an article a few weeks ago in which the National Hurricane Center stated it was not a hurricane when it hit land in NJ.
What made Sandy so damaging was not the winds, it was the storm surge. Because of its huge size, it was able to push so much water onshore, but it was not a hurricane.
Check out the Hurricane's center website: "Sandy transitioned into a post-tropical cyclone just prior to moving onshore near Atlantic City, NJ. For a complete summary of Sandy, view the National Hurricane Center Sandy Tropical Cyclone Report."
Since it was a post tropical cyclone, which means it lost all characteristics of a hurricane, there were not even any hurricane or tropical storm warnings issued by the NHC. There were high wind warnings and there were peak gusts mainly in the 60s and 70s mph. A hurricane is sustained winds of 74 mph for at least one minute.
But again, the damage was caused by the storm surge not wind.