Best Time to Go
The Silicon Valley area enjoys a temperate climate all year round so any time of the year can be a good time to visit. Summers are rarely too hot to stand, with average temperatures staying around the high 60s and 70s, and few days creeping into the low 80s.

Winter temperatures rarely go below the 40s. This area offers quite a few amusement parks and gardens to visit, which are particularly nice in the spring and fall. These seasons are less crowded and enjoy pleasant weather, and visitors also have the advantage of off-season rates on flights and hotels, especially after Labor Day.

Average Weather
Silicon Valley enjoys a year-round pleasant climate with temperatures never getting too severely hot nor too cold. The lows in the winter months hover around the 40s, while the highs of the afternoon crawl into the 50s/low-60s. Spring and late fall tend to have a comfortable average high of 65 degrees, getting down to a night low of about 45 degrees. Late summer and early fall temperatures can get up to the low 80s, with lows averaging 56 degrees. There's always a risk of fog in Silicon Valley, especially in May and June, but as a rule of thumb the climate is seldom something to worry about.

Transportation
If you want to explore the whole Silicon Valley area and visit each city en route, it's usually advisable to rent a car. This gives you the freedom to visit some of the smaller, less accessible towns in the valley and to set your own schedule for exploring wineries, amusement parks and so on. There are lots of car rental services at either the San Francisco airport or the San Jose airport. You'll also find car rental locations in many of the other Silicon Valley towns like Palo Alto and Los Gatos.

If renting a car is not your preference then there is some good public transport available, especially between the largest cities like San Jose and Palo Alto. From the San Jose airport it's easy to find a train or bus (many are free shuttle services) to your final destination in Silicon Valley, and the journey should take anywhere between 30 minutes and two hours, depending on your final destination and time of the day. There is a convenient and reliable train service called CalTrain that connects San Francisco and Gilroy, serving much of the Silicon Valley area in between.

Getting around the cities can usually be achieved on light-rail trains, trolleys or buses that service the entire area. For example, in San Jose light-trains connect major attractions, shopping malls and so on. During the summer months you can ride an historic trolley in the downtown area. Another example is the Menlo Park Midday Shuttle, which offers free transport between certain points in Menlo Park and Palo Alto on weekdays only.

In-Season Costs
Silicon Valley is an affluent place and as such you can expect to pay a little more than some other areas for a hotel room. Many hotels cater to the business community and can be quite pricey at $150+ per night.

For the best deals, try the chains hotels. Like most areas, summer prices are higher, and you can usually hope to get a better deal in the winter months. If you book early you can usually get a fairly good rate. There are enough hotels in every price category, from budget to luxury, so it should be easy to find one that suits your budget.

Day Trips
Visiting the entire Silicon Valley area is probably the best day trip (or two) you can take during your stay. You can't get an overall picture of the valley if you only visit San Jose. Silicon Valley starts about 50 miles south of San Francisco and extends down 50 miles to Gilroy. The area in between these two points has some 14 or 15 different communities and almost all are worth exploring. Day trips can take you to places like Palo Alto, where you'll likely tour its main attraction, Stanford University, or to Menlo Park to visit the fine Filoli House and Gardens. Alternatively, head to the charming town of Los Gatos to visit the Old Town or bring the children to the new Bonfante Gardens Theme Park in Gilroy. You'll find parks and gardens, amusement parks and museums and much more in your travels around the Silicon Valley.

For a day trip out of Silicon Valley, San Francisco is easily accessible both by car and train. This city is famous as a great place to visit, and you'll probably want to see such renowned sites as the Golden Gate Bridge, Alcatraz Island, Fisherman's Wharf, San Francisco Zoo and so on.

Also within relatively easy distance for a day trip is Oakland. Often overshadowed by its more popular neighbor, Oakland itself offers many attractions for the visitor, including the Oakland Zoo, the Oakland Museum of California, as well as plenty of fine restaurants, shops and entertainment.