If you are moving to Silicon Valley, whether San Mateo or Santa Clara County, you should know that things are a little different in fall and winter than they are in spring and summer. Here are just a few areas that might not be intuitively obvious to the newcomers.
First, a word on appearance. In Santa Clara County, we have two primary sets of hills – one closer to the Pacific Ocean and Monterey Bay (west side), and one closer to central California (east side). Because our local weather is dominated in very large part by the Pacific Ocean, much of the weather blows in from the coast. A lot of the rain gets dumped in the coastal range, also known as the Santa Cruz Mountains. Less makes it all the way to Los Gatos, less still to downtown San Jose, and a much smaller amount to the east foothills and places such as Alum Rock Park. The coastal range (also called just “the hill” by locals) is green year round as it is full of redwoods and other trees which love the moisture. The east side, though, is more grassy, fewer trees, and gets far less rain. In winter the grasses are a lovely green. With drought or in summer, however, the grass turns brown or pale yellow.
For people coming from the east coast, the hills there are more likely green in summer and brown in winter. Here, though, it is the opposite. We don’t usually get rain in summer, so the grasses die and the hills go brown.
Rain, when we get normal patterns, usually begins in November and comes and goes between then and late April. In a typical year, San Jose gets 15-20″ of rain (Los Gatos more, the Los Gatos Mountains much much more). If we get an El Nino pattern year, temps will be warmer than usual and rain will be much more common than typical. It’s not much fun to have an El Nino year, but right now we desperately need the rain, so folks here are all hoping for it.
Second, a word on roads and travel. Silicon Valley enjoys a sub-tropical climate with mild temperatures and not too much rain, even in a normal year. With very little rain most of the time, our streets and highways can develop a dusty, oily film. Whenever we get rain after a dry spell, those highways and roads can be slicker than you might expect. It’s not that we need a ton of rain for the surfaces to become more slippery, either. A very small amount of precipitation can do the trick, so be careful!
If your destination requires going over “the hill”, be triply careful! Too many people, whether regular commuters or first time adventurers, either tailgate or drive too fast, and it can make it too easy for accidents to happen when a little weather is added into the mix. (more…)