From flexalert.com 

California-ISONorthern California - ONLY
Flex Alert issued by California ISO as heat wave intensifies
With hot temperatures bearing down on Northern California and with a major generation unit off line, the California Independent System Operator Corporation (ISO) is issuing a Flex Alert for Northern California Only on July 1, 2013, through July 2, 2013. No Flex Alert is issued for Southern California as temperatures moderate but watch for updates on www.caiso.com. Consumers are encouraged to reduce their energy use during the late afternoon when air conditioners drive consumption to the highest point of the day. Go to www.flexalert.org or www.caiso.com for conservation tips.
24-hours ahead: Northern California ONLY Flex Alert Day! on July 1, 2013. High temperatures are forecast throughout the state and region. Energy demand is expected to be high and Californians are asked to avoid using heavy electrical appliances until after 6 p.m. tonight.
Monday's forecast peak demand: 48,300 MW around 4:30 p.m.
48-hours ahead: Northern California ONLY Flex Alert Day! on July 2, 2013
Tuesday's forecast peak demand: 47,808 MW around 4:30 p.m.
72-hours ahead: July 3, 2013 No Flex Alert Day
Please monitor the California ISO website at www.caiso.com for updated information about the electricity supply. Track grid conditions in real time via Today's Outlook also available on smart phones. Go to your app store for a free download.
This advisory is based on the best data available at the time of its release. Grid conditions can change rapidly and are subject to change without warning. This forecast is accepted by the recipient on the condition that errors, omissions and/or changes to the contents shall not be made the basis for any claim, demand or cause of action against the California ISO.
Funded by the investor-owned utilities and authorized by the CA Public Utilities Commission, Flex Alerts are part of an educational and emergency alert program that informs consumers about how and when to conserve electricity.