The weather is sunny, sunny, sunny - what else do you need to know? Temperature around our house will be 25-30 celcius going down to 15-20 at night.
Evenings are cooler though so bring a warm sweater or fleece jacket (especially for the kids). (But then again we might have a heat wave but it's best to be prepared!)
Will it be warm enough to go to the beach? Well that depends, usual weather is that during the summer months the beaches will not get sun every day and when it is overcast it will be very very cold (15 celcius at best). And the water will always be too cold to swim (unless you like cold water).
Current weather in Sunnyvale: click here
San Francisco is always colder than the South Bay Area. Mark Twain supposedly said: "The coldest winter I ever spent was a summer in San Francisco".
Current weather in San Francisco: click here
For those that really want to see "tinsel town", you can go to the City of Angels.
Current weather in Los Angeles: click here