Although it doesn't have any firm boundaries, the Bay Area is composed of nine counties that include Marin, San Francisco, San Mateo, Santa Clara, Alameda, and Contra Costa. The southern parts of Sonoma and Napa counties are considered part of the Bay Area for this guide, since their culture and economies face towards the Bay.
Temperate in summer and mild in the winter, the Bay Area is an excellent place to visit year-round. The weather in the Bay Area is affected by microclimates, so certain parts of East Bay can be up to 15 degrees warmer than downtown San Francisco, and as much as 20 degrees warmer than the area around the Golden Gate bridge. Generally the closer to the ocean one goes the cooler it is, it is suggested that one keep that in mind when traveling around the area.
A small region of its own, the Bay Area still has distinct areas with their own attractions and cultures. The sub-regions of the Bay Area are described several ways, which may give the first time visitor the impression that the Bay Area is bigger than it really is. In fact, the unique geography of the Bay Area makes it relatively easy to get a sense of where you are.
Here's a handy rule of thumb: the telephone area codes 415 and 707 means the City or the North Bay; 510 and 925 mean the East Bay; 650 is for the Peninsula, and 408 and 831 are for South Bay numbers.
There are three major airports in the San Francisco Bay Area: San Francisco (SFO, located about 10 miles south of the city), Oakland (OAK, in the East Bay), and San Jose (SJC, in the Silicon Valley, about 1 hour south of San Francisco). All are served by discount airlines such as Southwest. All three airports may be reached by inexpensive public transit.
From the east, the entrance to the Bay Area is superhighway '''Interstate 80''', which wends its way all the way from New York several thousand miles to pass through Lake Tahoe and Sacramento and end up in San Francisco.
From the south, the lovely '''Highway 101''' runs from Southern California through the Central Coast to Silicon Valley and up the Peninsula to San Francisco. Some people prefer '''Highway 5''', which travels more directly through the San Joaquin Valley to highway '''580''' and then into the Bay Area through the East Bay.
From the North Coast or the Pacific Northwest, the story is similar. Coastal highway 101 is more scenic, while highway 5 is efficient but somewhat boring. Interstate 5 intersects interstate 80 in Sacramento, however, when coming from the north, Interstate 505 can be used to bypass Sacramento and get to the Bay Area quicker.
Parking rates in San Francisco can go up to $30. You can park at Bart parking lots: For example: Park in Colma parking garage $1 all day, free weekends and round trip BART from Colma to Moscone Center would cost $6.20.
The Bay Area is well served by a '''network of freeways'''. Highways 280 and 101 run up the Peninsula from the Silicon Valley to San Francisco, and 101 continues into Marin County across the Golden Gate Bridge. Highways 880 and 580 run the length of the East Bay, and Highway 24 runs out to Contra Costa County. 101 and 880, as well as most bridges, can be pretty heinous at commute times, however.
Beware that many Bay Area freeways tend to have dense traffic at any time of day or the evening. There is a proportion of "hurried" drivers that will zig-zag between cars at high speeds. In the North Bay, there are fast succession of freeway interchanges; a misunderstanding may land you on the wrong freeway, even on a bridge you do not intend to take. Interchanges are signposted with road numbers and compass directions, but these may be even confusing: the same stretch of road may carry several numbers and opposite compass directions between these numbers. Read a map carefully before driving or have a passenger watch for directions.
'''Bay Area Rapid Transit''' ([http://www.bart.gov BART]) is a nice regional train system that connects San Francisco to the East Bay and Contra Costa County, as well as parts of the Peninsula, the eastern half of Silicon Valley, and the San Francisco and Oakland airports. BART is also useful for getting around within SF and Oakland. Ticket prices vary by distance travelled, but usually run about $2-5 one way. Trains run about every 10-20 minutes starting around 6AM and closing just after midnight.
'''[http://www.caltrain.com Caltrain]''' is a commuter train system running from San Francisco, down the Peninsula, all the way to Gilroy. Ticket prices vary by the distance between stations, but usually run around $3-$6 one way. Trains run about once every half hour, on average, once an hour late evenings and weekends, with several more trains running during commute hours. This train service is not particularly fast; however, in a move to improve speed, many trains during commute hours run express or semi-express service, so they do not stop at all stations.
A full list of Bay Area public transportation agencies, as well as a refreshingly useful trip planner, can be found at the Metropolitan Transportation Commissions's web site '''[http://511.org 511.org]'''.
Be careful to check for ticks [http://www.cdc.gov/ncidod/dvbid/lyme/ld_prevent.htm] after hiking in fields in the bay area. There is a high rate of lyme disease transmission in the Bay Area. If a bulls' eye rash develops at the tick bite site, immediately seek medical help and treatment with antibiotics.