Weather Blog

San Francisco, where a week's worth of rain takes over 6 months to get

San Francisco, where a week's worth of rain takes over 6 months to get
A 5 MPH boating speed limit buoy is stuck in the ground as there is no water to be seen at Black Butte Lake near Orland Buttes Recreation Area Friday Jan. 17, 2014 in Orland, Calif. (AP Photo/Chico Enterprise-Record, Jason Halley)

As you've probably heard, much of California is in the midst of a terrible drought that threatens to break records (if they haven't already), and that's saying something for a state where droughts have been pretty intense over the last century or so.

While the Pacific Northwest isn't exactly overflowing with mountain snow this winter either, at least we have some, courtesy of a few storm systems that have at least nicked the area, and the big week of snowstorms that came through in early January in between our long dry stretches. California mountains have anywhere from 7-16 percent of their normal snowpack.

But it wasn't until I was peeking at some weather data from San Francisco that the depth of the drought really hit home. Going back to July 1st, how many days do think there has been measurable rain in San Francisco? I'll give you a hint: Normal is 33.

15? 10?

Turns out, it's not even a week's worth: Just six days. They have had one rainy day in January, two in December, two in November, none in October, one in September and none in July nor August.

Now, July and August are typically zero months there, and September and October average a combined four rainy days. But San Francisco is supposed to get 29 rainy days from November 1 through January 31, and they have... five.

To put that in a little perspective, Seattle with our January that is at the moment the sixth driest on record still eclipsed San Francisco's 6 1/2 month rainy day total in just one week!  We had seven straight days of rain between the 5th and 12th and still checks in at nine rainy days this month.

For the entire year, San Francisco ended up with just 3.38 inches of rain -- 17.27 inches below normal!! -- which shattered their all-time driest year. (Old record? 8.79 inches!) To compare, Phoenix had over 8 inches for 2013. And San Francisco has added a whopping 0.01" so far in January 2014.

The culprit is a generally static global pattern where a ridge of high pressure has frequently set up shop just off the Pacific Coast, providing a barrier to Pacific storms and sending the jet stream farther north into SE Alaska, where it's been a very wet autumn and winter. (That pattern has also been responsible for the frequent arctic outbreaks this winter on the East Coast.)

Unfortunately, things are not looking up for the next few months, and in fact NOAA is predicting the drought conditions will intensify across the Pacific Northwest as well.



"Drought is expected to worsen during the latter half of January across the Pacific Northwest," NOAA forecasters wrote in their latest seasonal drought assessment. "The poor start to the wet season with large precipitation deficits and very low snow-water equivalent values is likely to result in a continuation of drought through the end of April. Therefore, drought persistence is forecast for the Pacific Northwest."