Seattle's Climate

The perception of Seattle’s weather boils down to one word: rain. If you were to talk to anyone who’s not from the area about the Emerald City, that word is brought up a fair bit. The problem is, it’s not an entirely fair assessment of the local climate. The basic understanding of Seattle’s weather comes down to this - Seattle's climate has cool, wet winters and warm, relatively dry summers.

What’s in dispute is when does summer begin and end, and when does winter begin or end. The running joke in the area is that summer doesn’t officially start until July 5th. And winter? Well, winter in Seattle looks quite a bit like autumn on the East Coast. It’s often overcast, dreary, and punctuated by light rain.  Where, say, Boston has distinct winter season, with snow and ice ending up on the ground in copious amounts, Seattle rarely sees a snow day or has problems with ice, although they do happen every few years or so.  So when the region has a wet autumn, wet winter, and wet spring, it’s easy to say it rains in Seattle all of the time.

The statistics also tell us something else. Over the course of a year, a Seattleite will only see the sun about 23% of the time. There’s some amount of precipitation one-hundred and fifty two days a year. However, Seattle only sees about 34 inches of rain a year, and the airport has reported an average of 37.49 inches of rain. Compare that to Tampa, Florida which receives 46.5 inches per year or New Orleans, which brings in around 62.7 inches of rain a year.

It’s further convoluted by the fact that many areas within driving distance of downtown receives more rain. Bremerton, WA, fifteen miles to the west and across the Puget Sound, gets 56 inches of rain a year, and the Hoh Rain Forest in Olympic National Park can get 142 inches per year. Seattle’s reputation for rain is believed to true due to circumstance. It is overcast a lot, the areas around it receive a fair amount of rain, so therefore Seattle must get a lot of rain. 

But this isn’t true. Yes, it’s cloudy, and yes it’s wet, but the rain here is more of a mist than downpour. Seattle rarely sees a cloudburst, let alone a thunderstorm. Many residents pay attention to the type of rain, and then react accordingly. If it’s a light rain, many folk will go out without the urge to protect themselves from the weather. The locals can tell the tourists because the tourists bring the umbrellas.

The summer is a different story entirely, and the statistics bear this out.

This is one reason why people love living in Seattle. As dreary and wet the other eight months can be, the summer months are fantastic. It’s not too hot, and the rain is minimal.

** all data above culled from usclimatedata.com and http://www.ncdc.noaa.gov

The Faults in the Puget Sound Area

The Puget Sound, including the Seattle region, are seismically active. This is due to the dozen or so different fault lines in the region. If you’re visiting Seattle, the Seattle Fault is the one most local, but all provide some measure of risk, some greater than others.

The Seattle Fault was first identified in 1965,, but wasn’t classified as an actual, active fault until 1992. It runs east/west. Its eastern most terminus (where it starts/ends) is likely where it intersects with the Rattlesnake Mountain Fault, somewhere around Fall City, about 40 miles to the east. Its western terminus is still unknown for certain, but it is known that the fault line extends beyond the Puget Sound through Bremerton.

As for the specific location of the fault line? Take a look at the location of Interstate 90 from Seattle to Bellevue. The Seattle Fault line parallels that nicely. You’ll also note that the fault intersects through the stadium district, just south of downtown. All of that land there? Much of it is man-made, filler created from the dirt of the Denny Regrade.  This is the city of Seattle’s biggest earthquake risk, a fault line that runs underneath a section of land that is likely to liquefy when the big one arrives.

However, the Seattle Fault is not the only fault line in the region. There’s the Tacoma Fault down by, well, the city of Tacoma. To the north, running north-west/south-east is the South Whidbey Island Fault, which also runs into the aforementioned Rattlesnake Mountain Fault. These are but a percentage of the amount of fault lines running in the Puget Sound area. Many, if not all, of these faults are actively seismic to some degree or another.  The bulk of the earthquakes in the area occur either in the area between Mount Rainier and Mount Saint Helens, or in the immediate Puget Sound vicinity. The fact that these regions contain a great majority of the State of Washington’s population is a well-known risk.

Why are there so many faults in the region? It would be simple to point out the fact that Seattle, as well as the rest of the Western states in America are part of the Pacific Ring of Fire, that stretch of earth that starts many miles south of New Zealand, heads up north through Indonesia and then Japan, turns right north of Korea and the Kamchatka Peninsula, through the Aleutian Islands, and then turns south along the west coast of Canada and the United States, and then continuing south through Costa Rica, Peru, and Chile. But this tells us more of “where” rather than “why”.

One of the theory as to why, harkens back to glaciation and the last major ice age to hit the area. Yes, this would be the same glaciation that helped shaped the Sound as well as the many lakes in the region. The theory is that, if you have an ice sheet that is five times taller than the Space Needle, that amount of weight is bound to do some measure of damage to the tectonic plates.

Speaking of tectonic plates, the third major risk of earthquakes comes from the Juan De Fuca plate as it drives itself east under the Cascadian subduction zone.  While technically not in the immediate Seattle vicinity (the Juan de Fuca plate is several dozen miles off of the Pacific coast, well into the Pacific Ocean), the sheer amount of potential energy that the plate can release will have an impact on all of the Puget Sound area to some degree or another. As a point of consideration, many experts believe that the Seattle Fault has the potential to produce a 7.0 magnitude earthquake.  Any sudden movement in the Cascadia Subduction zone has the potential to release a 9.0 magnitude earthquake.  In fact, that area had already demonstrated that level of destruction with the 1700 Cascadia earthquake.

The 20 highest summits of the United States

Rank    Peak            State        Elevation
1    Mount McKinley        Alaska        20,236 ft./ 6168 m
2    Mount Saint Elias    Alaska        18,009 ft./ 5489 m
3    Mount Foraker        Alaska        17,400 ft./ 5304 m
4    Mount Bona        Alaska        16,550 ft./ 5044 m
5    Mount Blackburn        Alaska        16,390 ft./ 4996 m
6    Mount Sanford        Alaska        16,237 ft./ 4949 m
7    Mount Fairweather    Alaska        15,299 ft./ 4663 m
8    Mount Hubbard        Alaska        15,016 ft./ 4577 m
9    Mount Bear        Alaska        14,831 ft./ 4520 m
10    Mount Hunter        Alaska        14,573 ft./ 4442 m
11    Mount Alverstone    Alaska        14,564 ft./ 4439 m
12    Mount Whitney        California    14,505 ft./ 4421 m
13    University Peak        Alaska        14,470 ft./ 4410 m
14    Mount Elbert        Colorado    14,440 ft./ 4401 m
15    Mount Massive        Colorado    14,428 ft./ 4398 m
16    Mount Harvard        Colorado    14,421 ft./ 4396 m
17    Mount Rainier        Washington    14,417 ft./ 4393 m
18    Mount Williamson    California    14,379 ft./ 4383 m
19    La Plata Peak        Colorado    14,343 ft./ 4372 m
20    Blanca Peak        Colorado    14,357 ft./ 4376 m

Mt. Rainier

So if you think that the lakes in the area have been around for a while (they’re roughly 12,000 years old or so, they are mere babes when compared to the Mount Rainier. “The Mountain” as it’s called by some in the area had its start some 840,000 years ago, when its earliest lava flows can be determined.  It took 340,000 for those lava flows to form the cone found serves as the foundation for the volcano/mountain we know and love today.

Mt. Rainier is an active stratovolcano, which is a formal way of saying it’s a conical volcano with periodic eruptions from time to time. If you made a volcano for your science fair, chances are you made a model of a stratovolcano. . Other well-known stratovolcanoes include Krakatoa and Vesuvius. For residents, that can be a terrifying observation if they were to give it any in depth thought. However, because Mt. Rainer can currently be considered “at rest”, it’s easy for the locals to ignore the sleeping giant south of Seattle.  It’s important to note that “At rest” is just another way of saying that the volcano is currently between eruptions, with the implications of that sentence being intentional. Mt. Rainier will erupt again, someday.

The last noted activity of Mt. Rainier was in December 1894, when local newspapers reported black smoke rising from the mountain’s summit.  But whatever activity had occurred on the mountain was minor in nature, and no lava flow was detected. The last lava flow eruption of Mt. Rainier likely occurred 2200 years ago. It’s easy to ignore the threat of Mt. Rainier when it hasn’t been destructive since the heyday of the Roman republic. 

The Mountain top most peak has an elevation of 14,417 ft. Geologists believe the mountain was once 16,000 feet but due to mudflows, glaciations and avalanches, its elevation decreased over time. Mount Rainier has 26 major glaciers, and has 35 square miles of permanent snow fields and glaciers. It is the United States' most glaciated mountain.

Mount Rainier's river valleys, forests and meadows were once inhabited by various Native American tribes, long before those of European descent had shown up. . The local tribes included the Muckleshoots, Puyallups, Yakamas, Cowlitz's, and the Nisqually. They referred to the mountain as Tacoma, Talol, Tahoma, Tacobeh, and Pooskaus, depending upon the tribe and era.

George Vancouver gave the volcano the name Mount Rainier in 1792,  in honor of his friend Rear Admiral Peter Rainier. In his journal of his trip to the Pacific Northwest, he states:

"The weather was serene and pleasant, and the country continued to exhibit between us and the eastern snowy range the same luxuriant appearance. At is northern extremity, Mount Baker bore by compass N. 22E.; the round snowy mountain, now forming its southern extremity, and which, after my friend, Rear Admiral Rainier, I distinguish by the name of Mount Rainier, bore N(S) 42 E."

The news got around fairly quickly, as Lewis and Clark's map from their 1804-1806 expedition refers to Mount Rainier as Mt. Regniere. Sure the spelling was off, but the name was recognized. However, throughout the 19th century the mountain was called both Mount Rainier and Mount Tacoma. It wasn’t codified as “Rainier” until 1890, when the United States Board of Geographic Names deemed that it would be named after the British Admiral.  As late as 1924, however, a resolution was introduced in the U.S. Congress to call it Tacoma.

The first people documented to have climbed Mount Rainier were Hazard Stevens and P.B. Van Trump, who successfully completed the ascent in 1870. The first female to complete the climb was Fay Fuller, in 1890. American naturalist John Muir climbed Mount Rainier in 1888. He wrote of the climb:

"The view we enjoyed from the summit could hardly be surpassed in sublimity and grandeur; but one feels far from home so high in the sky, so much so that one is inclined to guess that, apart from the acquisition of knowledge and the exhilaration of climbing, more pleasure is to be found at the foot of the mountains than on their tops. Doubly happy, however, is the man to whom lofty mountain tops are within reach, for the lights that shine there illumine all that lies below."

Approximately 13,000 people attempt to climb Mount Rainier each year, and it can take up to two to three days to climb to its summit. Its summits include Liberty Cap, Point Success, and Columbia Crest. From the top of the primary peak one can see a great distance, including Mount Hood, Glacier Peak, Mount Baker, Mount Adams, and Mount St. Helens which is around 90 miles away.

The Mountains and Volcanoes of the Seattle Area

Thanks to the Kitsap and Olympic peninsulas that help shape the Puget Sound, Seattle ends up situated between two mountain ranges.  There’s the Olympic Mountains located on the Olympic Peninsula approximately fifty miles to the west.  To the east, also roughly fifty miles away, is the Cascade Range.  Within the Cascade Range, located about 80-ish miles to the south east is Mt. Rainier.

Looking from Seattle across the Puget Sound, one can easily see the Olympic Mountain Range. Compared to the height of many of the peaks of the Cascade Range, the Olympics are smaller. The highest peak is Mount Olympus, clocking in at around 7900 feet.

However, what makes the Olympics notable is the fact that the range is part of the Pacific temperate rain-forest ecoregion, noted by the World Wildlife Fund as the largest temperate rain-forest ecoregion on the planet. This region runs from Prince William Sound in Alaska, all the way south through the Pacific Northwest, down to northern California. The forests that this massive, interconnected region contains are larger than any other ecosystem on the planet.  
However, to visit the Olympics from Seattle takes some planning, due to the Puget Sound. Either one has to wait in a car to pick up a ferry in order to cross the Sound, or the other option is to drive an hour or so to Tacoma, and cross the Tacoma Narrows Bridge.  From a purely logistical perspective, it is far easier to access the Cascade Range to the east.  Due to this, when a Seattle-ite talks about the mountains, they primarily mean the Cascades.

Specifically, the Central Cascades, which have loads of hiking, climbing, and skiing.  A quick 30 minute jaunt to Issaquah, WA via Interstate 90 is all that’s needed to get to the foothills of the Cascades.

The Cascade Range is considered part of the Ring of Fire, a region of the planet that contains about 90% of the world’s earthquakes, and contains about 75% of the world’s volcanoes, both active and dormant. It runs from the west coast of Chile, up north through the western coast of South America, then through the west coast of Mexico and the United States, up through the Pacific Northwest and into Canada. Around Alaska, it turns west, and heads over to Russia, before turning south to Japan, and the Philippines. It runs east-west around Malaysia, Indonesia, and New Guinea, before turning south again around Fiji and Samoa. It ends up just east of New Zealand.  Or, to put it another way, the Ring of Fire encompasses the border of the Pacific Tectonic Plate.  What this means is that Seattle shares similar risks to volcanoes and earthquakes as Japan and even New Zealand.

The mountain range of the Cascades run from northern California, to the Fraser River in British Columbia, which separates the Cascade Range from the Coast Mountains.  Included in this range are some of the more well-known mountains in the United States, including Mount Shasta in California, Mount Hood in Oregon, Mount St. Helens in southwest Washington, Mount Baker near the Canadian border, and Mount Rainier, about 85 miles south/southeast of Seattle.

The Duwamuish River

At the southern portion of Elliot Bay, beyond the man-made Harbor Island, is the mouth of the Duwamish River is the name of the lower 12 miles of the Green River.

The river has had a history of man-made upheaval and…well…Industrial contamination/poisoning. Until 1906, the White and Green Rivers joined around present-day Auburn, about twenty-eight miles to the south of Seattle, and then joined the Black River near Tukwila to form the Duwamish River. In 1906, after a massive flood, the White River changed course with the result being it emptying into the Puyallup River as it does today. With the confluence now gone, the lower portion of the White River is now simply considered part of the Green River.

In 1911 the Cedar River was diverted to empty into Lake Washington instead of into the Black River, the result of which included less water flowing in to the Duwamish. Finally, in 1916, with the opening of the Lake Washington Ship Canal, the lake's level dropped nearly nine feet and the Black River dried up. From that time forward, the point of the name change from Green to Duwamish is no longer the confluence of the Green and Black Rivers, though it has not changed location.

In other words, today the Duwamish River is part of Green River, but it used to be the result of the confluence of several other rivers that have since dried up, or have been diverted elsewhere.

Seattle’s economy used to be primarily driven by manufacturing, and all of the industrial aspects of that in which it entails. While the Seattle of today has a more diversified economy, what with the technology, financial, and bio-genetic companies in the area, manufacturing still exists.  This can be seen in the area of south Seattle, including the region bordering the Duwamish River.

The result of over one hundred years of industry in this region has resulted in a heavily polluted river. So much so that the Environmental Protection Agency has labeled the river a Superfund site, the environmental program established to address hazardous waste sites.

These pollutants have affected the local wildlife, including the chinook, coho, chum and steelhead, salmon that inhabit the waterways.  Many of the animal species found in or around the river contain an unhealthy amount of contaminants. In a memo from the EPA in 2008, they stated, “any type of fish or shellfish found in the river is unfit for human consumption. It was found that PCB levels in fish and crab that live in the waterway most of their lives are 35 to 110 times higher than in Puget Sound salmon.” Their Ecological Risk Assessment also found that river otters from the Lower Duwamish River might be exposed to such high levels of PCBs that the growth or survival of their offspring may be reduced.

Efforts are underway to clean up the area, with current estimates on completing the project pointing to sometime between 2016 -2020.

Lake Union

Lake Union from Gasworks Park

While Lake Washington is the de facto eastern border of Seattle, and technically outside of the city limits, Lake Union is a part of the Emerald City, as the city has developed around it.

It, like Lake Washington, was formed by the retreating Vashon Glacier, although it is certainly not as deep, and at five-hundred and thirty-eight acres, it is neither as wide nor as long as the lake to the east.

Native Americans of the Duwamish tribe lived on the shores of Lake Union for more than 5,000 years. They called it by two names that compared it with Lake Washington.  In Lushootseed (the Duwamish tribe’s primary language), it was XáXucHoo or Ha-AH-Chu (“littlest lake”).  In Chinook it was “Tenas Chuck” which means “small water”.

In addition to the lake’s year-round residents, there are also stories of other extended members of the Duwamish tribe coming from the local area to spend their winters in a seasonal camp at the south end of the lake.  The coastline of the lake provided wild roses, red currant and squaw berry bushes for the gatherers, as well as deer, elk, bear, and cougar for the hunters.

When pioneers arrived in Seattle in the 1850s, the Duwamish camp was in the southwest corner of the lake, near where Thomas Street and 8th Avenue North meet just north of Denny Park. The native inhabitants remained there, albeit with dwindling numbers, until 1875.

Lake Union also received its present name from Thomas Mercer, who predicted that canals would join Lake Washington to Puget Sound in a "union of water", with Lake Union being the body of water that binds Lake Washington to the Sound.

If you look at Lake Union on a map, it looks sort of like a deformed head of a rabbit, with the canal to the north-west forming its left ear, and the right ear being the water way to Portage Bay. The northern shore of the lake is home to Gas Works Part, and southern end of the lake is called the South Lake Union area. Eastlake and Westlake are the neighborhoods found on each respective shore. The names surrounding the lake are far more underwhelming than the use and impact of the lake upon Seattle’s history.

Lake Washington

Lake Washington, from a bench in Kirkland, WA

Lake Washington is the largest lake in King County and the second largest natural lake in the state of Washington. Seattle is found on the Western shore of the lake, Bellevue on the eastern, Kenmore on the Northern, and Renton on the south. Mercer Island sits just off of the western shore, in the southern half of the lake, which you'll barely get to see if you take Interstate 90 from Seattle to Bellevue.

The lake is fed by the Sammamish River at its north end and the Cedar River at its south. However, when we talk about "rivers", don't expect the grandeur of the Mississippi or Alleghany. These are smaller rivers, akin to creeks to those of us imagining the Thames or the Danube when we hear the word 'river'.

Lake Washington is a deep, narrow, glacial trough, created by the Vashon glacier as it receded from the area, roughly 12,000 years or so ago. The lake is 20.6 feet above mean lower low tide in Puget Sound, to which it is connected via Lake Union, the Lake Washington ship canal, and the Chittenden Locks. The canal is the only discharge from Lake Washington via the locks and dam at the western end. The development of the canals, dam, and locks resulted in the lowering of the lake 9 feet to its present level

Lake Washington was named by Thomas Mercer in 1854, when he suggested it be named after George Washington, as the new Washington Territory had been named the year before.

Other names for Lake Washington have included the Duwamish/Lushootseed name HAH-choo or Xachu  ,(translating into "great-amount-of-water"), as well as Lake Geneva, Lake Duwamish, and in Chinook (Chinook being the intertribal trading language),  it was called "Hyas Chuck," which means  "Big Lake."

Elliott Bay

Part of the Puget Sound includes Elliott Bay, and it is in this bay that Seattle is located.  The bay is easily defined, and extends southeastward between West Point in the north and Alki Point in the south. The Bay is fed by the Duwamish River, found at the southern end of the bay. Viewing from downtown, the river is obscured a bit by Harbor Island.

No one knows for certain for whom Elliott Bay was named. We do know that it was named by Lt. Charles Wilkes during the United States Exploring Expedition that took place between 1838 and 1842. Wilkes had the command of the expedition and had several ships under his command. However, there were three Elliotts under his purview. Jared Elliott, ship's chaplain, was disliked by most of the crew, including Wilkes. George Elliott, a ship's boy, had little stature in the crew, and had been recently in trouble for insubordination when Wilkes had named the bay. Midshipman Samuel Elliott was a member of the USS Porpoise survey crew that charted the bay. Considering Wilkes’ opinion on the former two candidates, it seems probable that Elliott Bay was named for Samuel, but there’s little in the way of objective evidence supporting this.