Seattle Space Needle Reflection at Night

The Truth About Seattle Rain

Raining in Downtown Seattle

Raining in Downtown Seattle

I am the biggest weather junkie I know.

Back in elementary school, I had to enter the Science Fair, so I built a gadget that was supposed to predict the weather. It took temperature, humidity, and barometric pressure readings, and using those three variables, it used an analog wheel with 0-100% drawn on the sides to point to the percentage of rain.

Being a smartass from an early age, I included a test tube with a probe which, if any moisture was detected, would immediately pin the dial to 100%.

Little did I know that I was ahead of my time. Even with multi-million dollar radars, this is pretty much the way meteorologists forecast today. In most cities, there is a rolling 20% chance of rain, which immediately jumps to 80%+ once it, you know, actually starts raining.

One of the reasons I love Western Washington so much is the wide variability of the weather. Rarely are two days here the same. Hell, rarely are two hours here the same. For anyone with an IQ north of 100, this is generally a good thing. When you look at the most highly prosperous, most highly advanced countries in the world with the highest quality of life, you’ll find that most of them have dark, cool, cloudy, highly dynamic weather.

I have many theories on why this is, but I’ll spare you the dissertation for the moment. By the way, a reader sent me this last week. Take it for what you will:

In any event …

Today, I was researching all kinds of local weather phenomenon when I came upon some obscure stats relating to hours of rainfall per year. I’ve already expounded on Seattle sunshine, so this time, I decided to tackle the wet stuff.

You see, people in Seattle readily concede that it rarely rains hard here, but, as they will tell you … “it rains often!”.

How often?

Let’s find out.

Over the course of a year, it rains for 822 hours in Seattle. This means that there is a 9.4% chance that it will be raining in Seattle at any given time. I suppose you could round it off and just call it 10%.

Now, this doesn’t sound like much, but the number is significantly reduced by the relatively rain-free 5 months between May and September. We get 751 hours of rain between October and April, which means that there is a 15% chance that it will be raining at any given time during the rainy season.

This is a lot of rain, but it’s certainly not “all the time” that Lisa Van Cise and the California transplants would have you believe. Even during the rainy season, there is an 85% chance that it will not be raining at any point you walk out the door. Over the course of a year, there is a 90% chance that it will not be raining in Seattle at any given time.

If you think we have it bad, steer clear of Olympia where it rains 30% more often, or the Aberdeen/Forks coastal area where it rains 110% more often.

Of course, even though it doesn’t always rain in Seattle, we still get far more than every other major U.S. city.

In Los Angeles, it rains 2.1% of the time.
San Diego 2.0%
San Francisco 4.1%
Denver 4.3%
Las Vegas 1%

For some reason, nobody studies these things on the East Coast, so I can’t go further west than Denver. That being said, using sample standard deviation along the coastal and inland areas of the West Coast, and using (San Francisco x 1.25) for the East Coast, suffice to say that it rains in Seattle 2-3 times more often than in any other U.S. city … on average.

This is a lot, but even during the rainy season, it’s certainly nowhere near all the time.

So there you have it. Once again, a shitty indie blog has given you something that the highly paid professionals in the local media will not.

The hype-free truth.

Use it wisely.

5 comments to The Truth About Seattle Rain

  • Kip

    Where did you find the hours of rainfall by month? I’m trying to compare Seattle to Dallas, and have only found inches of rain stats. Thanks!

  • wafflesnfalafel

    That is great data – you hit the nail on the head. It’s the amount of time where some rain falls that some folks get all cranky about. I figure it just gives us more incentive to get out and do stuff when it’s beautiful, (like today.)

  • matguy

    I heard way back, and I recite it way too often for something I never fact checked, but aparently durring the core Summer months, like June, July, August, Phoenix supposedly gets more rain than we do.

    I looked at a few historical rain charts for a few minutes for the 2 cities, and in a very un-scientific cursory overview, there seems to be something behind that statement.

    • Seattle Rex Seattle Rex

      It’s true for a month.

      Phoenix gets 1 inch of rain in July, Seattle gets .77 inches.

      Consider that today is August 14, and so far this month, we have had 0.00″ of rain. We’ve only had an inch in the last two months. Yet, everyone is complaining about our “non-existent summer” because it’s been 77 degrees instead of 80.

      The reality distortion field is strong when it comes to Seattle weather. For 6 months out of the year, we get less rain than the US average. Only our falls and winters are excessively wet, but we don’t get the blizzards and hurricanes that other cities get. Do we really want the summer that the East Coast has gotten? I’ve honestly never seen a whine factor so high.

      If everyone that hated the weather here left, can you imagine how affordable the area would be? Can you imagine how light traffic would be?

      I wish they would put their money where there mouths were.

  • Chuckreis

    “So there you have it. Once again, a shitty indie blog has given you something that the highly paid professionals in the local media will not.”


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