Wednesday search challenge (11/7/12): How much DOES it rain in Northern California?

Sometimes the simplest questions can lead to relatively tricky searches.  This is usually the case when the data you’re looking for isn’t just lying around on the floor of the internet, but is something you might have to assemble yourself. 

I was standing in the microkitchen at work last week waiting to make my café latte when a couple of us started talking about the weather during the past month. 

“Seemed awfully rainy to me,” a friend pointed out.  “Is this something new?  Or has October always been rainy in Northern California?” 

I’ve lived just south of San Francisco for over 25 years, and MY opinion was that this October seemed rainier-than-usual as well.  But you know how impressions are—they’re notoriously subject to all kinds of mis-rememberings, and in particular, the human ability to give accurate summaries of events over the long scale is really quite poor.

So I thought I’d just look it up—but this bit of weather data turned out to be a bit tricky, and leads to this week’s Search Challenge…

Can you find OR create a chart like this one I've sketched below showing each year's total October rainfall at SFO to answer the question:  

Did it rain more in October, 2012 than in any October during the past 10 years? 

My ideal chart for October rainfall at SFO.  (This is made-up data for the purpose of illustration.)  

To make it simple, let’s check the rainfall during October at SFO.  I know that accurate weather data will be available at the airport.  (Although you need not limit your searches to only FAA data. Any reasonably reliable rainfall weather data will do.  It just has to be measured at SFO.)  

As usual, please let us know HOW and WHERE you found the info, along with an estimate about how long it took you to answer the question (or generate the graph). 

Search on!