Equinox Thursday: Halfway to Summer

Tomorrow morning at 9:57am we’ll see the Spring (Vernal) Equinox in the northern hemisphere.


What does that mean?

The earth orbits around the sun, but the poles are not lined up directly perpendicular to the orbital plane.  Our planet is actually tilted about 23 degrees from vertical.  That means that at one point in our orbit the southern hemisphere is receiving more energy from the sun than the north and six months later it is reversed.  That’s how we end up with summer and winter, the effect being more pronounced (generally) the farther you head away from the tropics.  If you visit a tropical area you’ll find that “summer’ and “winter” aren’t really in their vocabulary since the sun is always almost directly overhead.  Tomorrow we’ll be halfway between the two points, thus the Equinox which means “equal night”.  Day/night are very close to equal in late March and in late September.

Of course you might then wonder why we aren’t halfway to the hottest time of the year climate-wise?  If the average high in Portland is 44 at the coldest and 82 at the warmest, why isn’t the average high in the lower 60s?  It’s because it takes time for the heat to accumulate on the land and in the oceans, and they are both slow to lose it, thus the delayed seasons.  If we’re talking just energy from the sun, we should be halfway through spring right now.  Obviously we aren’t.

Another misconception is that it’s winter right up until tomorrow morning.  That’s not really true either; because the coldest 3 months of the year at our latitude are December-February, not mid December through mid-March.  Take a look at the average monthly temperatures here in Portland:


Notice that March is not only warmer than December, but even a bit warmer than November!  Even if you take the coldest four months of the year, March still isn’t included and is definitely not a winter month in the Pacific Northwest.  That said, it’s a little easier to get snowfall to lower elevations in March than November.

Meteorologically we consider winter in the Northern Hemisphere as December-February for the reasons mentioned above.  How was this winter in our area temperature-wise?  Take a look at the national temperature departure from normal:


Note we were generally near normal across Washington and Northern Oregon and above average farther into the state (of Oregon).  Now I’m not into conspiracy theories, generally, but I do notice what someone else already did.  You have to look very closely to see the below average temperature areas but the opposite, above average, sticks out great due to the color table chosen by NCDC.  Much of the nation was very cold, yet this map seems to minimize it a bit.  But, maybe it’s just me.  Anyway, if you look closely at Oregon you see something interesting:


The chart above shows temperatures for Zone 2 in Oregon, the Willamette Valley area.  We had our coldest winter since 2008-2009.  Yet:


This chart shows the high desert areas of Oregon east of the Cascades had their warmest winter in about 8 years.   What?  Most likely due to the frequent inversions.   Remember all the days Salem sat in the 30s while Bend and Burns made it into the 50s?  That explains it.

What about precipitation?  No big surprise here, parts of the Pacific Northwest, especially along the coastline are in the MUCH BELOW NORMAL category.  The farther south you go along the West Coast the drier it was:


Poor California, and they are just about out of time to get significant rain this season.

So this winter was definitely drier than normal and a bit cooler than normal here in the lowlands.  Once again…a weird winter.  So far March is running wetter and warmer than average.

By the way, do you know what would happen if we were orbiting the sun without that 22 degree tilt?  There wouldn’t be any (temperature) seasons.  We would just stay the same year-round.  And you can probably guess what it would be like if we were tilted a full 45 degrees?  Even more extreme changes from summer to winter.  In that case the sun would be directly overhead at the summer solstice and it would be on the “arctic circle” with the sun hardly rising at all at the winter solstice…brrr!

Chief Meteorologist Mark Nelsen

59 Responses to Equinox Thursday: Halfway to Summer

  1. Rustic Fare says:

    Thank you Mark (and all your team) for your daily weather information. Since I moved to Salem almost a year ago, it is useful to know about it. I need to get used to this climate but so far I survived heat above normal, rain below normal, some valley fog, cold below normal and snow… I love Oregon!!! 🙂

  2. Jason Hougak says:


  3. Jason Hougak says:

    Spring break and it’s going a great ski week with the snow level between 4-5K and maybe lower late in the week. Enjoy the nice weekend, looks mighty stormy as we close out March, “roar!”

  4. schmit44 says:

    3/20/2014 Oregon (All) Temperature Summary

    High:65 at BROOKINGS( 79 ft)
    Low: 44 at Medford, Rogue V(1329 ft)

    High:22 at HOWARD Mt Howard(8150 ft)
    Low: 6 at ANEROID LAKE #2 (7300 ft )

    Largest Diurnal Change: 37 degrees
    Lorella (59/22 ) (4160 ft )

    Heaviest Rainfall:
    0.39″ at CW3999 Hillsboro(150ft)
    0.39″ at WANDERER’S PEAK(4350ft)

  5. ashley watson says:

    I may have to move to sherwood. Does anybody know if the hills and mountains around there get good snow and if real estate is spendy. heck I wonder if corbett is even a good place to live. Where is the best place for snow around Portland that is reasonably affordable.

    • Jason Hougak says:

      Aside from this strange winter, I’d say anywhere above 1,000 feet greatly increases your chances for snow in the PNW. The higher… the better. Plus you don’t get trapped under those inversions! 

    • marinersfan85 says:

      I live in SHerwood. It isn’t any different than living anywhere in the valley when it comes to snow. Although in February we had over a foot total. One thing that is exciting here is when we get those SW wind events, Sherwood is a great place for them. If the forecast calls for 30-40 mph gusts, 45-50 is a good bet here. Thunderstorms also seem to NOT miss this area.

    • marinersfan85 says:

      Rex Hill in between Sherwood and Newberg goes up to about 1500′. I don’t know what prices are like though.

  6. Jason Hougak says:

    Is schmidt44 a computer? We get the climate summary but never any input for this source.
    “NOVA… danger danger…no disassemble… no disassemble… Johnny 5 is alive!”

  7. Jason Hougak says:

    Mark we need weather action now!!! Is this what happens when the weather calms down? Winter blogging about arctic air and polar vortex with snowstorms is much more exciting.

    • High Desert Mat (Model Rider) Redmond Or says:

      I agree Jason. Summer is great for the outdoors but winter is just alot more exciting.

    • Mark Nelsen says:

      Yes, this blog is often quite dead for days/weeks at a time during slow weather in the warmer half of the year. Action always picks up in November again.

  8. Lurkyloo says:

    WTH went on here since I last looked at the blog? Absolutely ridiculous. Someone needs to get a grip. There’s that one place down in Salem that maybe could help that one person …

  9. boringlarry SE of Sandy1600 ft says:

  10. It’s only been bulbs and flowers here – Didn’t expect nuts to ripen for a couple months yet…

  11. Larry says:

    Wow looks like the loonies have climbed out from under their rocks for the Winter. Welcome to Spring!

  12. MrTriforce says:

    In fact I have agents of my own Mark that follow you and know where you live and you’re security set up.

    I am tired of you making fun of anybody who dares not tow the party line.

    Is this blog about freedom of speech or Mark’s Ego Yahoo Weather Blog where it’s okay to post as long as it agrees with Mark’s views?

    Funny I don’t recall that being ANYWHERE in the blog rules section but I’ll double check just to be sure.

    • High Desert Mat (Model Rider) Redmond Or says:

      I have a little brother that is 21 and he has severe autism as well. He says the same kind of outrageous nonsense too. He told me once that the federal union of the United States was coming for me. I just laughed it off. Hopefully Mark does too.

    • gidrons says:

      I thought he has Asperger syndrome, one of the milder forms of autism?

    • gidrons says:

      Kyle I mean, not your brother.

    • boydo3 N Albany says:

      He’s being sarcastic in regards to Mark’s comment on the very light blue color on the map….I think 🙂
      Right Kyle? Back me up on this before they come to take you away haha!

    • this blog, Kyle, is about weather. Not anyones agenda. The fact that you bring religion, politics and other rantings is probably why no one takes you seriously. Talk about the weather. Or even the occasional sports thing or funny joke. But dude. Turn down the whack-o-meter.

  13. MrTriforce says:

    Hi. I want to let you know Mark that you are going to get killed for you’re atheist agenda for silencing those who speak up and for you’re conspiracy against me!

    You’re conspiracy will not go unchallenged!

    I am going to put in end to this and if you think you can send you’re time travel agents out after me guess what? I’ll destroy them too!

    You’re entire operation is to put it nicely…………on the line!

    Faux News at it’s best!

    • marinersfan85 says:

      Red Pen Police – Your not You’re. Good to see you back Kyle. You insight is always so thought provoking.

    • MamaReen says:

      Oh no. Red pen police. “Your” as in “Your insight is always so thought provoking”. 😉

    • High Desert Mat (Model Rider) Redmond Or says:

      Uh wow!! Someone has forgotten to take their meds again. Kyle, pop a few of your necessary pills and get back to us.

    • W7ENK says:

      Kyle, I hope you realize this statement could be considered a direct threat upon the life of a public figure, especially when followed up with the statements you made later (above) about following Mark to his home, etc…

      I’m sure some real agents from the FBI will be speaking to you in short order, posting crap like this on a public internet forum. Asperger’s or not, Autism or otherwise, your disability is not an excuse for this sort of talk. The little $#!+head that shot up Sandy Hook Elementary was autistic, and we all saw what he did.

      Mark, I seriously think it’s time you actually take real action over this, and not just laugh it off and sweep it under the rug.

      No excuse. Not funny!! >_<

    • pappoose in scappoose says:

      Clearly stepped over the line here, MrTriforce.
      No doubt Mark hasn’t observed this threat against his life.
      The big guns will soon be out!

    • David B. says:

      @W7ENK – I agree. Death threats are no laughing matter, and should not be waved off. And they are not free speech either. They ought to be reported.

  14. David B. says:

    The reason for the difference in shades seems to be that the extremes of warmth were more extreme than the extremes of cold. A large area of Southern California was the warmest in history, but none of the East/Midwest were the coldest in history, just much below average.

  15. Mike (Orchards 255') says:

    Great post Mark, one of the best I’ve seen.

  16. alohabb says:

    Snow/rain mix falling in Hwy 18 outside Lincoln City

  17. Jason Hougak says:

    I’m wondering if during the ice age the earth had more of a tilt or was it from volcanic debris blocking the sun?

    • Mark Nelsen says:

      I think one climate cycle is based on the “wobble” of the earth. A slightly greater tilt would cause some climate change.

    • gidrons says:

      There is a wobble in the earth’s axis and there’s also an eccentricity to the earth’s orbit. From wikipedia:

      The Earth’s axis completes one full cycle of precession approximately every 26,000 years. At the same time the elliptical orbit rotates more slowly. The combined effect of the two precessions leads to a 21,000-year period between the astronomical seasons and the orbit. In addition, the angle between Earth’s rotational axis and the normal to the plane of its orbit (obliquity) oscillates between 22.1 and 24.5 degrees on a 41,000-year cycle. It is currently 23.44 degrees and decreasing.

  18. Jason Hougak says:

    Got 45 tilt

  19. Jason Hougak says:

    The three gorges dam is causing the earth to have added tilt. The east coast can blame China for the frigid winter.

  20. pdxgeologist says:

    I’ve now lived in the tropics (Panama) for close to a year and a half. It’s funny that you mentioned the lack of vernacular for summer and winter down here. They do talk about summer – but in Panama, summer = December through March – the dry season, even though we are 7 to 10 degrees north of the equator. I’ve never heard anyone say spring or fall, or winter.

    BTW, just found out I’ll be moving back to PDX just in time for my favorite season, Fall!

  21. schmit44 says:

    3/19/2014 Oregon (All) Temperature Summary

    High:69 at Hayes Hill (US 1(1640 ft) & ILLINOIS VALLEY(1389 ft) & PROVOLT SEED ORC(1180 ft)
    Low: 46 at EMIGRANT LAKE AT(2042 ft) & EW3480 Ashland(2333 ft) & NERRS METEOROLOG(9 ft)

    High:30 at HOWARD Mt Howard(8150 ft) & Mount Hood Meado(6601 ft)
    Low: 10 at Horse Ridge (US (4160 ft )

    Largest Diurnal Change: 47 degrees
    CHRISTMAS VALLEY (59/12 ) (4360 ft )

    Heaviest Rainfall:
    0.30″ at TIDEWATER(2035ft)
    0.28″ at DW6452 Russellvi(1329ft)
    0.26″ at LOG CREEK(2800ft)
    0.26″ at HEBOWX Mt. Hebo(3160ft)
    0.26″ at CW6318 Welches(1283ft)
    0.26″ at CEDAR(2220ft)
    0.24″ at DW9126 Brightwoo(1336ft)

  22. karlbonner1982 says:

    I think it’s safe to say that unless we have a big stretch of very cold showery weather (1000′ snow levels) right beyond the 7-Day for several days – then March 2014 is going to end up warmer than average. I remember last year the days at DLS were slightly warm, but the nights were a fraction of a degree on the chilly side so the mean was less than half a degree F above climo.

    But this year we’ve just had too many balmy days and almost no serious March chill after the freak ice storm at the start of the month ended. Other years we CAN get lots of cold blustery days in the 40s and low 50s in March. I think The Dalles is up to 11 or 12 days in the 60s now? And we have a few more before the rain comes next week.

    I think it’s safe to say this will end up being the “nicest” March in the eastern Gorge area since 2005, when we had that crazy warm stretch in the first half of the month (but I was living in Eugene at the time). But this year may actually be better than 2005 in one way: the mild and frequently sunny conditions have been frequent and recurring, from the 4th of the month on through the 24th. The chilly periods in the past week aren’t all that far below average for mid-March. It just FEELS really clammy when you add in the 30-40 mph wind gusts.

    But a bunch of warm and pleasant spring days scattered throughout most of the month? I can’t complain!

  23. W7ENK says:

    The Sun looks so much smaller than the Earth in that graphic… and yet, that death ray… I feel so bad for those poor people in Liberia. I hope they have sunscreen!!

  24. karlbonner1982 says:

    I’m sure some people on this blog would love to increase the tilt of the axis to about 26 or 27 degrees, to get more extreme seasons. MWAHAHAHA….

  25. Sifton says:

    Indeed, good points Mark. & to all the winter “purists” who still go by dates on a calender; take this fork & shove it!! Winters over & here comes sweet sweet summer!!!

    • pappoose in scappoose says:

      Only in your dreams. We’ll still have some sloppy wet flakes mixed in some AM. Hahaah!

    • Sifton says:

      Sorry poose but those days are long gone! Doesn’t snow here like it did in the ‘old’ days, a man made phenomenon rather than an natural one imho……

    • pappoose in scappoose says:

      Very possible, Sifton, hope you’re wrong!

  26. Dave in SW PDX (235') says:

    Great post, Mark. Lots of information for weather geeks (like me) to ponder. Looks like it could be another bad fire season for SW Oregon, unfortunately.

  27. Eastman(Parkrose/NE Portland) says:


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