There are numerous reasons for these grid failures, ranging from system or equipment malfunctions to natural disasters, and even more frightening: cyber terrorists. Whatever the cause, it's crucial to be prepared for this unfortunate situation.
From Earkling 56 Family Blog:
The best thing you can have during a power grid failure is a positive attitude. Make sure to do whatever you can to encourage hopefulness and keep spirits high.
In addition to the right attitude, I recommend doing the following to properly prepare yourself and your family:
Create a storage space that can be easily accessed in the dark
Stockpile at least two-weeks worth of supplies
Design a plan for preparing food, sanitation, living / sleeping quarters, entertainment (especially for children), and rationing for fuel and power sources
Store jugs of water in the fridge now to be used during an outage to keep food from spoiling; however, once the water melts, it should be used for cleaning or flushing, not drinking
Store a flashlight or lantern by every bed
There are ten integral categories that should be part of every well thought out power grid failure disaster plan:
Drinking Water
Food
Lighting
Heating
Communication
Sanitation
First Aid
Protection
Additional Items
Backup Power Systems
This blog post goes into further detail on each of those categories and how to best procure them.
We recommend clicking on the link above and reading the entire article.