Berkeley Labs has released a report on electricity reliability on the United States. This study looked at reliability data collected by electricity distribution companies, and created two metrics.

• System Average Interruption Duration Index (SAIDI) which indicates the amount of time a customer is without power over the course of a year on average.
• System Average Interruption Frequency Index (SAIFI) which is the average total number of times a customer experiences a power interruption over the course of a year.

The study looked at power disruptions from storms like Hurricane Sandy, and without major events like this to determine power reliability. When major storms are included then the study finds that hotter days, higher wind speeds, and higher annual precipitation results in an increase in SADI (see the report for all the details).