We likely won't see enough of an effect that can't be confused with the normal network variance. While the news is hyping this up significantly, just remember a few key things:
1) The hurricane is not going to be affecting that many people overall (outside of heavy rain/wind). The vast majority of the east coast will still have power and internet service, though it might not be as reliable as they're used to.
2) Coastal cities tend to have fairly high living costs per square foot, and higher electric costs, so the concentration of huge mining farms is likely very small in areas affected by the hurricane.
Not trying to start an argument or anything but...
It wasn't a hurricane. I know, I know, the news stations were blasting out all over the airwaves that it was, but it wasn't when it made landfall.
I wouldn't say 6.5 million people without power isn't "affecting that many people overall".
Probably the highest concentration of BitCoin nodes on the planet is located in the northeastern U.S. While the number of nodes does not directly indicate the total hashrate from an area, it's a pretty good correlation.
On the other hand, I doubt the hashrate drop from that area will be large enough, or long enough to make any major change to the next difficulty adjustment.
