Micro-ClimatesLocals to the San Jose area (Silicon Valley, Santa Clara County) know, and newcomers often do not, that we have micro-climates here. Our weather is mild everywhere, of course – we enjoy a “sub tropical climate” where citrus grows and palm trees thrive – but it varies a lot nonetheless.

What kind of variation exists in Santa Clara County’s weather?

Consider that our terrain is shaped somewhat like a funnel with the San Francisco Bay on the wide end, and the two mountain ranges making up the sides of the funnel, narrowing at its base (near Morgan Hill).

View Larger Map

Together with our funnel shaped valley, the Pacific Ocean and the San Francisco Bay are the major influences on our climate. The Santa Cruz Mountains are warmer and wetter than the eastern foothills. The Pacific Ocean brings in the rain, fog and winds pulling storms in from the ocean to the valley. Much of the weather stops at or near the coastal mountains, though, and the influence lessens as you go east such that the east foothills are very, very different from the Santa Cruz Mountains. The areas close to the bay get more breezes than those sheltered by smaller valleys or nooks.

So what are Silicon Valley’s Micro-Climates?

Here are a few basic notes for newcomers:

  • Temperatures: The Santa Clara Valley gets warmer the further south you go – so Morgan Hill and Gilroy can be quite a bit hotter than downtown San Jose (which is nearer to the Bay) in summer. Proximity to the bay means a little less heat in summer, more breezes, so Los Altos is about 5 degrees cooler than Los Gatos in summer.
  • Wind: Most afternoons in summer at around 4pm -6pm or so (late afternoon), a breeze blows from the north to the south, primarily along the San Francisco Bay and east foothills. Also in summer, if it’s terribly hot inland, the coast will be shrouded in fog and Mother Nature will try to cool things off by bringing fog in to the valleys. This means wind through the passes and often you can see what almost looks like a waterfall of clouds and fog draping over the low points in the coastal hills. It’s quite pretty. It can also be quite windy where those low points are as the fog and wind struggle to squeeze over the passes and into the hot valley. Thanks to the breezes, summer evenings tend to be very comfortable here.
  • Rain: The west valley areas (Almaden, Los Gatos, Monte Sereno, Saratoga, Cupertino, Los Altos, Palo Alto) up against the coastal foothills get more moisture than the east valley areas (Milpitas, North San Jose, Alum Rock Park area, East San Jose, Berryessa, Silver Creek).
  • More Rain: The coastal foothills and “mountain communities” of the Santa Cruz Mountains (Redwood Estates, Holy City etc.) get about double the rainfall of downtown San Jose – that’s why it’s so green! The reason is that the water comes in from the Pacific, which is the dominating factor in our local climate.
  • Snow: What about snow? It doesn’t snow in San Jose except when there’s a very extreme storm blowing down from Alaska – this happens about once every ten years and the snow, if it hits the ground at all, will only last a few hours at most. It is a freak then when it lands on the valley floor, and everyone’s delighted to see it because it is so unusual. As you can imagine, the site of snow on a palm tree is most bizarre.
  • Although snow is almost never seen on the valley floor, it does snow each year in the east foothills, also known as the Diablo Range. Our landmark there is Mount Hamilton, where there’s an observatory. The snow doesn’t tend to last more than 4 or 5 days but it is pretty to see. Less common, but also happening annually, is snow falling on the coastal range. Why is there snow on one set of hills but not the other? The same reason one is very green with redwood trees and the other is grassy with only a few oak trees: proximity to the ocean and its impact on climate.

Micro-climates are something to be aware of when relocating to the San Jose area. There’s a big difference in summer highs between Gilroy and Palo Alto. There’s quite a bit of difference in rainfall between the Santa Cruz Mountains and the Alum Rock Park area. Even in the town of Los Gatos, there are pockets which get more and less wind, higher and lower temps. If you are relocating to Silicon Valley, please contact us at Luxor Real Estate Group and we can help you understand the microclimates and get the lay of the land. We are anxious to help you understand these more subtle issues as well as the more obvious ones of housing cost, schools, and so on. We know the area and are happy to introduce our clients to all the fine points of life here in what was once called “The Valley of Hearts Delight”.





  • Mary Pope-Handy

    Silicon Valley Realtor, selling homes in Los Gatos, Saratoga, San Jose, Silicon Valley, and nearby since 1993. Prolific blogger with a network of sites.

    View all posts