My company is in New Jersey and lost power during Hurricane Sandy. We had a meticulous business continuation plan and our colocation site had us up and running within 24 hours. The plan assumed that we would just log in from home and keep the company running. But in north central Jersey, nearly every customer had no electricity for the first few days, literally 4-5 million people with no lights and no heat, (I was one of them,) but also no Internet connections, no wifi, etc. By the time the colo site was up, most of our workers could not be contacted because their cell phones had run down and most landlines these days rely on cable or optical modems that don't run without power. No one had Internet access for the same reason.

If you have a BC plan, great, but you should examine every contingency and not just assume "that won't happen." Our assumption that the business might be down but "of course" the workers could just log in from home was, in hindsight, rather stupid on our part.

I just wanted to emphasize Steve's comment: