To write a summary, you want to start with when and where the hurricane formed. From there, you'll want to explain all the areas that were affected by this storm (much of the East Coast). You'll want to focus on the areas where the storm had the most effect.
Describe the wind speeds, and direction of the storm when it directly hit certain states. Explain the damage and records made by Hurricane Sandy. There are quite a few facts that you would want to include in your summary. For example, millions of businesses and homes were without electricity, the coast guard had to do quite a few rescues, and hundreds of citizens had to retreat to shelters. However, in your summary you are going to want to give the specific numbers.
I would conclude by explaining that there hasn't been a storm like Sandy since, and the facts that made Sandy different from other storms. Good luck!