Will cell service stay up in the event of a power outage in Northern California?

[wwayer]

PG&E has floated the possibility of a major power cut in Northern California this week. Realistically, if a multitude of counties lose power, will cell phone service continue to function for the duration of the outage?

[pwg]

Unless the cell towers have also backup generators, when their backup batteries have gone flat, there will be no cell service.