Weather Blog

Seattle's secret to staying thin (in the yearly rain department)

Seattle's secret to staying thin (in the yearly rain department)
Those who have lived around here for a while probably know this statistic -- despite our rainy reputation, Seattle is nowhere near the rainiest city in the United States. Many places that have sunnier reputations -- such as Miami, Chicago or New York, actually get more rain than the 37 inches or so we do.

Another city on that list: Houston, which averages 46.07" a year. But they get nearly 50 days less a year with rainfall. How do they do it?

They get their rain in big, quick bunches. For example, since April 13th, Seattle has received 0.90" of rain.

During one stormy day on April 19th, Houston received 0.96".... in 10 minutes. Going further, that thunderstorm brought 1.46" in 16 minutes (or, about as much rain as we received in the entire month of February) and 2.52" in 35 minutes.

On the other hand, as I hinted earlier, Seattle gets about 150 days of rain a year, while Houston is just over 100. Plus, Seattle has *way* more overcast days -- 226 vs. just 160 for Houston.

So that's how they get ahead of us in the yearly rainfall department, without the rainy stigma. In Seattle, with our moist flow off the Pacific Ocean, it can rain for days, but not amount to much in the rainfall bucket. That's because the ocean is a big moderating force that typically keeps thunderstorms and their big, heavy rainfall events at bay.

In Houston, you have access to a lot of warm, tropically humid air from the nearby Gulf of Mexico. Warmer air can hold a lot more moisture, and thus when it rains there, it pours, and that's how it can rain for a few minutes and out-do a week's worth of rain in Seattle.

(One item where they do go hand-in-hand with Seattle -- that storm struck on a Saturday. We can certainly sympathize.)

Put another way for Seattle, we average 822 hours of rain a year -- or that means it's raining 9.4% of the time averaged over the year. (Or, put even another way, that means it rains just under 2 1/2 hours every day.) In the winter, it's worse -- about 13% of the time, and it's much better in our drier summer.

But at least it doesn't rain an inch every 10 minutes :)