Weather in Silicon Valley and the San Francisco Bay area

November 8, 2011 at 7:20 pm | Posted in Uncategorized | Leave a comment
Tags: , , , , , , , ,

Once we decided to move to California, I started looking at the weather in detail to help choose a place to live. This actually turned out to be very complicated (but very interesting) because the Bay area has many microclimates. (According to Wikipedia, a microclimate is a local atmospheric zone where the climate differs from the surrounding area.)

A warning: this whole post is about weather. If you aren’t interested in weather, you may want to just give this one a miss.

For example, let’s look at three different cities that span all of Silicon Valley:

San Francisco – 22 inches of rain per year:

Mountain View – 15 inches of rain per year:

San Jose – 15 inches of rain per year:

The differences are especially noticeable in the summer: in August, San Francisco’s average high is only 69 compared to Mountain View’s 79 and to San Jose’s 87. Which might not seem that unreasonable until you realize how close they all are — SF and SJ are only an hour apart and have a difference of almost twenty degrees!

So what’s going on? Why the microclimates, and how can we use this information to make sure we live someplace warm?

Well, let’s look at a map of the area:

As I mentioned in my last post, the term “Silicon Valley” generally refers to the area between San Francisco and San Jose. Now let’s look at the terrain version of this map with some added notes:

Even though this is labeled, I’ll describe it anyway:

  • The Santa Cruz mountain range (yellow arrows) runs NW and SE. On the map you can see that the southern “side” of it is all green with plants, whereas the northern side is much more brownish gray.
  • Silicon Valley is the area between the red arrows.
  • The San Francisco Bay is specified with blue arrows. The Golden Gate bridge is at its mouth to the Pacific on the west.
  • The area on the NE side of the Bay is generally called the “east bay,” (green arrows) and several people have told us that it’s kind of a crappy area.

Now it just so happens that the weather in this part of the world generally comes up from the ocean to the southwest. So when cold and rain and clouds and etc. are blowing NE towards Silicon Valley, an interesting thing happens: they hit the Santa Cruz mountains. And just like a stunt motorcyclist who rides up a ramp, all the weather and precipitation from the ocean shoots way high up in the atmosphere and continues its northeast-ward path too far up to cause any rain. You can see evidence of this on the mountains themselves: on the ocean side, they’re all green and lush from where the rain constantly hits them. On the land side, though, it’s actually quite dry. (This area is called a rain shadow.)

Over time, of course, the weather drifts back down and begins raining on land, but by this time it has moved even further northeast and has missed Silicon Valley entirely. (A similar thing happens in Seattle, actually — downtown Seattle is in the rain shadow of mountains to the west, so it gets far less rain than many of its more easterly suburbs.)

But this is certainly not the only effect. Let’s look at another one:

As I said, the weather is heading NE from the Pacific. At the bottom of this image, you can see the last effect I discussed: the red arrows show the cold air moving NE and the orange arrows show the weather shooting up when it hits the mountains. But take another look at that mountain range: it pretty much stops at the town of Pacifica (slightly below the blue arrows near the middle of the map). This means that unlike Silicon Valley, San Francisco really has nothing to shield it from the chilly Pacific air. Consequently it is actually a pretty cool city (and it is even colder than Seattle some of the time even though SF is at a much lower latitude).

Once the cold air passes through San Francisco, it continues right across the Bay without any obstacles in its path. Then it hits the east bay and makes them colder and wetter as well. Not as cold, of course, because that weather has been warming up a little over the land, but still much colder than sheltered Silicon Valley.

Along similar lines, once that weather has come inland north of the Santa Cruz mountains, some of it will reach the northern part of Silicon Valley. In particular, San Bruno (where we are staying right now), Burlingame, and San Mateo are much cooler than San Jose (which is at the southeastern edge of Silicon Valley and can be seen two maps up from this one).

There are other effects at work here as well, but these are the main ones I’ve been able to find. I know practically nothing about weather, but this post is what I’ve been able to put together from an evening of reading various weather blogs. And I’m half writing this because nobody seems to have written an article like this before — this is the article I was trying to find and didn’t seem to exist. =)

So to generalize: San Francisco and the east bay are cold and wet. San Jose is warm and dry. The Silicon Valley cities between them vary more or less linearly.

We’re hoping to find an apartment in Foster City, which is still pretty warm despite being close to chilly San Bruno. Driving to Mountain View these days is lovely — I keep my top down all day and drive around without a coat and it almost makes me forget that there even is a cold Seattle where I couldn’t go jacket-free all summer long. It’s nice. =)

Mom visiting

November 21, 2010 at 8:59 pm | Posted in Uncategorized | Leave a comment
Tags: , , , , , , ,

Mom at a park near Alki beach with the Seattle skyline in the background.

This past Wednesday Mom flew in from Cleveland and she’ll be here through this Friday. We’ve had a nice visit so far, with trips to Alki Beach, Marymoor dog park, Pike Place Market, Olympic National Park, Hoh Rainforest, and Ikea. Tomorrow we’re taking the clipper to Victoria for a one-night trip that will have us back home Tuesday night, and while there we’re planning to see Butchart Gardens and a bunch of touristy Victoria stuff.

It’s gotten pretty cold this week, which hasn’t bothered mom or Blake much but has been pretty unpleasant for me. On the up side, we had a few hours of snow today and it was delightful. (Somehow I don’t mind the cold so much if I’m all bundled up and cozy in a hat and scarf and there are snowflakes drifting all around.)

The forecast for Victoria tomorrow. Yipes. I didn't even know there was an igloo icon. :-/

Unfortunately, this evening I looked up the weather for Victoria tomorrow and it included a hilarious and foreboding icon that I’ve never before seen: an igloo. It used words like “frigid” and “cold” and “3.54 degrees”. I’m breaking out my ski gear from Colorado to keep warm, since I hope to be able to walk around Butchart for more than five or ten minutes without turning into a popsicle.

Our trip to Olympic National Park was pretty spectacular even this late in the year. We woke up early and caught the ferry to Bainbridge Island, drove 90 minutes to the park’s visitor’s center, then got back on the road for a beautiful 2.5-hour drive to the Hoh rainforest. We took several opportunities to stop along the way and take some photos as the mood struck us, but eventually we remembered that it gets dark here at 4:30 and we had to hustle the last hour or so to avoid arriving at the rainforest in the dark. As it was, we only walked around the Hoh for about twenty minutes before we had to head back for fear of hiking through the wet woods in the frigid night. (The park ranger kindly lent us a flashlight in case we had trouble finding our way back to the parking lot in time, but there were no problems.)

The Hoh is a beautiful park and is unlike anything I’ve ever seen before. I didn’t even know there were rainforests with deciduous trees and pine trees instead of palms and parrots. Because it was pretty dim and I didn’t bring my tripod, the photos I took are kind of underwhelming. (I intend to see the Hoh again when it’s warmer and greener and I have a tripod and maybe a new lens.) Even though all the deciduous trees were brown and it was really cold, it was still pretty neat. Though I bet it’s even more spectacular in the spring.

Anyway, I’ve got to pack for Victoria and exercise and get to bed soon, so please enjoy these photos.

Driving into the Hoh Rainforest

Some elk drinking on the river next to the road

The rainforest! (Yes, that's snow on the ground.)

Mom looking up at a 270-foot-tall tree (!)

Oh, and an update on our loud neighbors: the night after we left the note, the music was booming again as usual. So the next morning I stopped by the leasing office and mentioned it to the office manager, and she said she’d talk to them that afternoon. Since then we’ve heard some booming music in the afternoon and morning, but never at night. It’s still a little irksome in principle, but I can be happy with that. It’s not too disruptive if we’re not trying to sleep. Though I’ll be happy when we have a house and all the walls belong to us alone. =)

PS – If you’re interested, you may want to check out my photo-a-day blog, Out Our Window, which (predictably) has one photo each day of something taken out our window here in Seattle’s Chinatown.

“Hope you like rain!”: The climatological facts about Seattle

July 26, 2010 at 3:52 pm | Posted in Uncategorized | 2 Comments
Tags: , , , , , ,

Do you know what is the appropriate thing to say when you find that someone is moving to Seattle? I’ll give you a hint — it’s not “Hope you like rain!” As it happens, I do love love love rainy days — but Seattle is not the rain capital of the world (or even the US) that everybody thinks it is. From Wikipedia:

At 37.1 inches (942 mm)[80], [Seattle] receives less precipitation than New York, Atlanta, Houston, and most cities of the Eastern Seaboard of the United States. Seattle was also not listed in a study that revealed the 10 rainiest cities in the continental United States.[81] … Thunderstorms occur only occasionally. Seattle reports thunder on just seven days per year … For comparison Fort Myers, Florida reports thunder on 93 days per year. Kansas City reports 52 ‘thunder days’ and New York City reports 25.

Don’t get me wrong — Seattle does have more rain than Austin. But as a rain-lover this is just fine with me. Whenever I see a glimmering 20% chance of showers on the weather forecast, I watch the radar all day in hopes that whatever little baby shower is floating around will float right over here to our house and then hang out for a while. (This happens wayyy less than 20% of the time. I think there must be some geographic/climatic condition that makes our particular spot receive unusually little rain.)

Another less popular but still frequent response we often get is, “Hope you like snow!” This is also not the right answer. Due to Seattle’s proximity to the ocean, the weather actually stays pretty temperate despite its northern latitude. In fact, Seattle gets an average of only 13 inches of snow per year. Compare this with Cleveland’s 56.9 inches, New York City’s 28.4, and Lubbock’s 10.2. In fact, Seattle gets the same amount of snow annually as Richmond, Virginia — not exactly the snow capital of the world. (You can check the annual snowfall for a bunch of US cities at the NOAA’s site here.)

If you compare Seattle to Austin, here’s what you get:

Two charts displaying weather statistics for Austin and SeattleYou can see that Seattle is only a little bit colder in the winter but way less hot in the summer (and there is way more rain). If you want to see these charts on Wikipedia, here are Seattle’s, Austin’s and a page explaining how to read this kind of chart. Although I’m sure I’ll be a bit colder in the winter, I’m generally pretty happy about the upcoming change in climate.

So! What is the correct response when someone says, “We’re moving to Seattle”? It’s “Congratulations!” :D

When to plan a wedding (especially outdoors!)

April 12, 2010 at 7:03 pm | Posted in Uncategorized | 1 Comment
Tags: , , , , , , ,

This afternoon I discovered a great tool to help decide, climatically, on what day to have a wedding. I wish I had found this when choosing our date, but we didn’t have a lot of flexibility so it probably wouldn’t have mattered.

The tool is a little section of called “monthly history.” In case you’re not familiar with it, Wunderground is one of my favorite weather sites — it has a great interactive map that lets you get exactly the information you want.

The planning tool, however, is here and looks like this:

Wunderground Monthly History

Monthly history for April 2010

For each day it tells you the record and average values for high/low temp and precipitation. Then once the day arrives, it tells you the actual temperature. The best part is, you can look at a month (or more detailed info for a particular day) for any arbitrary time! I was pleased to see that the average amount of rain on our wedding day is only around 0.1 inches.

(Though really if it rains it’ll be okay. I love love love rain and we have contingencies for mud and almost-rain and full-fledged rain, and it’ll really be just fine no matter what. Weather, do your worst! I am not afraid!)

Blog at
Entries and comments feeds.