February 28, 2016

Seattle and Western Washington have the Longest Spring Season in the Nation!


Public Talk: Weather Forecasting: From Superstition to Supercomputers

I will be giving a talk on March 16th at 7:30 PM in Kane Hall on the UW campus on the history, science, and technology of weather forecasting as a fundraiser for KPLU. This will be a fun, educational exploration of the amazing story of of weather forecasting's evolution from folk wisdom to a quantitative science using supercomputers. General admission tickets are $25.00, with reserved seating and VIP tickets (including dinner) available at $100 and $ 1000, respectively. If you are interested in purchasing tickets, you can sign up here.

There are many superlatives regarding Northwest weather:  wettest region in the lower-48 states, world record annual snowfall (Baker), foggiest location in the U.S. (Cape Disappointment), and greatest non-tropical windstorm (Columbus Day 1962).   But there is another one that few talk about:  the longest spring in the nation.
Astronomical spring is, of course, the three month period from March 20/21 to June 20/21.  But meteorological/biological spring can greatly differ from astronomical spring.  Here in Seattle,  spring arrives early and leaves late.

I like to tell folks that typically spring begins in western Washington the third week in February (let's say Feb. 25th) and ends in mid-July (local meteorologists like to use July 13th).  Look outside now:  flowers are blooming everywhere, weeds are growing, and the grass is getting longer.   After Feb 25th, the chances of major flooding, low-level snow, and strong windstorms plummet.  And we all know that June is often cloudy and cool and we don't make the real transition to reliable summer weather until mid-July. A spring of 4.5 months.
But let me go further.   Not only are our springs the longest, but we probably have the longest springs in the nation.  Prove it, you say?   OK, let me try to do so.

First, we need an objective measure of spring.  I will propose that spring is the period bracketed by two transitions:
  1. the rise in maximum average daily temperatures from below 50F to above 70F
  2. the rise in maximum average daily temperatures from below 70F to above 70F
Below 50F you feel cold without a good jacket or sweater, above 70F a tee shirt will do.   Objective measures.

Locations where the daily high temperature never falls below 50F never have real winter and thus never truly have a spring.  As illustrated by the map of maximum January daily temperatures (January is normally the coldest month), there is no real spring in much of California, southern Arizona and Nevada, Texas, and much of the SE U.S.  Average high temperatures, typically rise about 50F each day.  Region's without spring.  Depressing.

Here in Seattle, the average high crosses 50F in late February and rises above 70F on June 23rd. About 4 months. A very gentle rise of temperature from New Years until summer.

In contrast, for Chicago the story is very different.  The rise about 50F occurs on roughly March 17 and the climb above 70F around May 15th.  Two months of spring, half of that enjoyed by Seattle.

New York?    A rise above 50F on March 18th and a climb above 70F around May 20th.   Two months.

Mile-high Denver?  The transition across 50F on March 2 and the rise above 70F on May 15th.  2.5 months.

Portland, Oregon, which is warmer than Seattle?  The rise above 50F on Feb 13th and the climb above 70F on June 1.  3.5 months
I have done this exercise for another two-dozen locations and the answer is the same: 


Imagine what the Seattle Chamber of Commerce could do with this information. Ads reveling in Seattle, the Springtime City, or Seattle City of Endless Spring, or Seattle's Eternal Spring.   Almost enough to make you forget about the traffic.

The inquisitive among you might be asking:  why does Seattle have such a long spring?  I believe the answer goes like this:

Seattle's marine climate is dominated by the Pacific Ocean, whose surface temperature even in midwinter only drops to around 50F.   We are isolated from the cold air of the continental interior and our air passed over the warm ocean rather the cool snow-covered interior.  Our average wintertime maxima are relatively high (low to mid 40s) and so when the solar heating starts revving up in February, we quickly climb above the 50F mark.   Thus, our early start to spring.

But the ocean cuts both ways, with the nearly constant 50F coastal waters working against any rapid increase in temperatures, even with the sun strengthening rapidly in March and April.  More continental climates (and that is really most of the U.S.) don't have such an oceanic restraint and warm rapidly.   Furthermore, the extensive low clouds of the eastern Pacific in spring and early summer (think June gloom) slow our warming further.   Only in July, when the building East Pacific ridge causes less onshore flow (as northerly flow increases), does the clouds relent and we surge into summer territory.

There are other related records that are worth noting, such as the longest spring roll (1428 feet) created in Indonesia.  But in many ways, our spring record is far more impressive and important.

And there has been lots of coverage of places with endless summer, but spring, the season of life and rebirth, is certainly superior.


Northwest Weather Workshop

The big local weather gathering is less than a month away (March 4-5, Seattle).  If you are interested in attending, the agenda and registration information can be found here.  This gathering is the place to be if you want to learn more about local weather research and operations.  You MUST register to go.


  1. So do those places with no winter (since they have no spring) also they would also have no autumn? So, yes, endless summer across the southernmost states…

  2. Cliff,

    I've noticed that in during January and February in the North Interior/Whidbey Island we've had several wind advisory level wind events, but the Seattle weather service office has been under forecasting our winds by about 10-15 mph. They have not issued wind advisories for any of our recent events. I'm curious why their models keep missing the higher winds we've had. I'm also disappointed that we haven't had much warning for some higher gusting winds. In Langley we've had gusts up to 40, and further north in the 50 range. Have you noticed these forecast discrepancies too? What do you think the reason is?

  3. Don't be depressed about east Texas. We moved here two years ago from Tyler. Spring begins in mid-February (plum, quince, daffodils) and continues with azaleas, dogwoods, and other plants until about mid-April. Summer heat (by Texas standards) doesn't set in until May usually. East Texas has four seasons: beautiful spring, hellacious summer, colorful fall, and short winter. It's a nice place to live except for summer heat, insane politics and extreme religious views.

  4. I have to agree with freia. My mother lives in Tyler, and if spring is heralded with flowers, east Texas has spring in spades. I will never get over the wisteria blossoms fifty feet up into the trees. Or the redbud. Or the azaleas. Or the paintbrush and gaillardia and a dozen other kinds of wildflowers.

    That said, I do *not* visit her between Easter and Halloween. Summer is absolute hell down there.

  5. Yep, I moved here from upstate NY and I have always called this place "the land of endless spring." There are only one or two weeks a year (over 90's in the summer, and an occasional weeklong cold snap in the winter) that you wouldn't find in a Northeast spring. One of the downsides is that all this spring weather (even in October, November, and December) is that it makes it so hard to remember what month we are in here in the Northwest - I get confused all the time about that.

  6. Most of our springs are not great. Too much lingering rain and dreariness. Part of the joy of spring is the promise of sunshine, and we just don't get enough of that too brag about our springs.

  7. Sure it's a long Spring but it's kind of a crappy season around here. Lots of rain in the lowlands and kind of marginal skiing conditions in the mountains. Not much to brag about ...

  8. The corollary to the longest spring is the shortest fall. Balmy summer weather persists late into September in our region -- sometimes into October as well. The crash from summer to winter takes only about 45 days, between 10/1 and 11/15. Fall colors are fleeting, with the most color found among the ornamental plantings of red maple in the suburbs.

    We do indeed have beautiful, lengthy springs, but we pay for them with our dramatically abrupt autumns.

  9. I just love that I'm already able to work on my garden (and for an ex-Michigander, doing that in February is something I only imagined doing after I crossed the Rainbow Bridge), and I can continue to work in my garden until well into October.

    As far as comments about sun go, that's not a real problem here in Sequim. Spring is very sunny, combined with just enough rain to make things grow without irrigation (unlike summer).

    We pay a few dues in mid-November to mid-January for all this, but if the calendar got stuck in sunny April or May, with the wild rivers in full song, then this truly would be heaven.

  10. Springs are very long here. However, using temps above 70 to mark the beginning of summer reflects a very Northwest-centric definition of spring. Much of the country would consider temps in the 70s typical of spring or fall and 80s marking the beginning of summer warmth. This would definitely be the case in the two other parts of the country I've lived (New England and the Rocky Mountain region). It is difficult to find an objective measure that folks from all over the country would agree on and perhaps using an absolute temperature isn't the best way to define spring. Of course, if you use numbers higher than 70 that just makes our spring even longer! By some standards, the Northwest is in almost perpetual spring.

  11. I love the long Spring like months in western Washington and the gradual unfolding of thousands of species of flowers.

    By Midwestern standards, Seattle does not have a 'winter' and summer is rather short.

    Seattle's rainy season, November - March, rivals Minnesota's winter season, November - March.

    Guatemala is known as the "Land of Eternal Spring". Spring has more than one definition.

    Global temperatures are at record warmth, from WU:

    Unprecedented February warmth in Eurasia
    December 2015 and January 2016 were Earth's warmest months in recorded history (expressed as the departure of temperature from average), and record-smashing heat in February is making this month a threat to join the parade. Two northward extensions of subtropical heat--one in eastern Europe and one in central Asia--led to phenomenally mild temperatures for February in the last two weeks. At least a dozen countries set or tied their all-time records for February during the latter half of the month.

    Not to be totally outdone, the midsection of North America had an impressively mild weekend, with temperatures between 55°F and 60°F setting daily records across southern Canada from Edmonton to Toronto. Top pick among the U.S. records: Bismarck, ND, where the 73°F high notched on Saturday was the state’s warmest for the entire month of February in 126 years of record-keeping, a full 41°F above Bismarck’s average high for the date of 32°F. Thanks to WU weather historian Chris Burt for catching this noteworthy statistic. Monthly record highs were also set in Mobridge, SD (73°F) and St. Cloud, MN (58°F), as noted by weather.com.

    Let's not forget about Fiji's recent Cat 5 hurricane, Winston:

    The storm killed at least 42 people, making it the deadliest in Fiji history.

    The government of Fiji estimated on Thursday that the cost of the disaster would be at least $468 million, making it the costliest tropical cyclone in South Pacific history.

    Winston's damage is roughly 10% of Fiji's GDP
    if the U.S. had a 10% hit to its GDP, that would be a roughly $1.7 trillion, on par with 15 simultaneous Hurricane Katrinas.

    Hurricanes feed off warm sea surface temperatures. Raise the global temperature by 2 C and hurricanes will grow even more fierce. Glad I don't live in a hurricane prone area! Months of spring much better than 185 mph winds.

  12. How ridiculous to imply that the entire southern U.S is a region without spring. That is in fact the loveliest season in much of that area. I went to
    college in New Orleans and was more appreciative of and cognizant of spring glory there than I ever have been here in my native western Washington. Which isn't to say our long, mild spring isn't pleasant, but it can often seem tedious. Not sure why a month of June
    gloom and waiting for summer until mid-July is anything to brag about. Of course, the last thing this region needs is to blow our trumpet more and attract yet another onslaught of newcomers.

  13. Sorry, Cliff, but you've got two major facts wrong here.
    1. Central North Carolina very much has spring. NC is the "Dogwood state," a well-deserved moniker that would be impossible without expression of spring weather following an actual, if not always snowy, winter. It also has a lower minimum temperature than us.
    To be blunt, the USDA hardiness map calls BS on your theory! Raleigh, NC, (27608), is hardiness zone 7b, with an average minimum temperature of 5 to 10F. Bellevue, WA (98008), is hardiness zone 8b, with an average minimum temperature of 15 to 20F -- TWO hardiness zones WARMER than your so-called "springless" Raleigh.
    2. Everyone knows summer begins on my birthday, July 11.
    I do love springtime here, though my allergies to tree pollen make it slightly less pleasurable than I want it to be.

  14. For times like last week, I like the term "faux spring" for this area. The sun comes out, the temperatures approach 60 F, young men start to appear on the streets of Seattle in shorts and flip flops. A few plants in protected areas start to bloom and give us all hope. The stores put out their first round of annuals.
    But, alas, it is "faux", and many of those newly planted annuals soon degenerate into soggy, flowerless blobs as they, like the rest if us, have to enjoy the temporary light while it lasts, and then hunker back down and wait for the real thing.
    Indeed, we have a spectacular spring blossoming here, but it doesn't really begin for another month in most of the area, and even then it means mild but seldom sunny days with a slow crawl out of the moss and puddles.

  15. The vigor of spring seems to be a direct function of latitude. Get north of 60 degrees, and the "vigor" is astounding, with every plant fighting for sun and growth with a phenomenal blooming. Short summers mean they have little time to do their thing, so not a moment is wasted.

    But I recall living in Florida when Spring was weak but notable, but had far less effect on plants. After growing up in Michigan, I thought all the plants and most of the people were pretty lazy down there when it came to Spring. Why wasn't everyone planting?

    Lots of vigor here in the PNW as well. I plant trees and shrubs like crazy in February and March, and they always do well. Bare root trees are like plant bombs waiting to go off and our Spring is perfect to light the fuse. The muckies are usually gone by early March (in Sequim anyway), so tilling and tractor work is possible. Greenhouse gets opened on most days to give the young plants a taste of the great outdoors. That glorious sun has real heat in its rays by now.

    March 1 is when I start cutting grass. This year, some of my neighbors started in mid-February because that's when the annual grass grow started in Sequim. Native bushes started leafing out about ten days ago.

    As you can tell, I love Spring. And I think Cliff is right on with a start date for Spring in the third week in February. Or so my plants tell me at my house.

  16. Cliff, a bit off topic. Any thoughts on the many recent articles this week like this discussing Co2 rise on the West Coast indicating earthquake threat?


  17. Cliff, any thoughts on the recent articles about the spike of West Coast Co2 indicating earthquake threats?

  18. Last year I had reservations at Paradise Jnn for early August to photograph the wild flowers on Mount Rainier. The flower show--spring on Mount Rainier--came a month early. I cancelled my reservations at Mount Rainier. Instead, I went to Sunrise in early July for the flower show--before that road is normally open.

    Any predictions as to the timing of wildflowers in the Cascades this year?

  19. I feel much better doc. I think I will go out and get some Seattle Sunshine. It comes nicely wrapped in raindrops this time of year. Where is Emmett Watson when we really need him. Oh and I might suggest that instead of having the longest Spring we actually have the 'most' springs as in Spring happens a lot ... you just have to run outside and catch them before they leave.

  20. I wonder worldwide which city/region has the longest Spring (and how that compares to Seattle)? I have a friend in Sydney who believes it's Medelin, Colombia, "The City of Eternal Spring." But if its true that without Summer there can no Spring, then certainly there cannot be eternal Spring as well, right?

  21. I always like to think of the beginning of spring as when the average nightly low temps rise above 32F. In my experience all over the east coast, this coincides well with grass turning green and starting to grow, and honeysuckle and lilac leaves appearing on trees (Like the national phenology network graphics suggest). It is hard to define the end of spring, but I would generally suggest for most of the nation it is when temps rise well into the 70s consistently (this may or may not coincide with the full leaf out of deciduous trees). Having lived at latitudes from 36N to 44N across the east coast, spring seems to be longest in the south, while it is much quicker in the north. Local climate and oceanic weather influence (as well as elevation) can also play such a major role. It's a fun subject!

  22. Nah not even close ive lived in washington, northern California, and the southeast. Washington definitely had the shittiest spring. Norcalhad the best and longest. Especially since u can vary ur elevation super quick on west spope of Sierra. In the foothills spring starts feb 1st. Around placerville the poppys come out by mid to late march and u can still find spring in the meadows around tahoe in july!all this within one hrs drive.best spring on earth.the southeast is a bit shorter but really gorgeous from march til june. The problem w Washington spring is it has colder night temps n no sun so it just doesn't feel as amazing as a true spring.to call the entire south depressing n having no spring is a straight up lie.sounds like you have been in the dark damp too long. Maybe u should come experience the warmth n beauty of a real epic c
    Sierra Nevada spring n maybe u wont be so grumpy and ignorant enough yo tell us who live with an amazing long spring that we dont have one cause you made up a conveniently excluding definition of it that is false. True spring is when its nice outside n the flowers are blooming in mass!enjoy your mushrooms we will be skipping thru fields of poppys lupine and dogwood blossoms for over 5 months in the northern Sierra!


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

Is Global Warming Causing Aircraft Turbulence to Increase?

 After the turbulence encounter by a Singapore Airlines aircraft,  there has been a slew of articles claiming that severe turbulence inciden...