First Cool Month Since March; Feels Like October!

9pm Sunday…

It’s been a very quick switch to not just early Autumn weather the past week, but it feels more like October with highs struggling to reach 70 some days.

Month Climate Temps Calendar

We’re running slightly below average for the month with no sign of warmer weather over the next 10 days.  That tells me we could actually end up with a cooler-than-average month.  That hasn’t happened since March.  And the rain is starting to (slowly) add up; we picked up another .35″ in the city today for a monthly total of 1.55″

Rainfall so far this month_compared to normal

That puts us above our typical September rain of 1.47″.

There were people worried in mid-summer that “Summer would continue into November” or it “would never rain again”.  Always keep in mind with weather that we have short-term memory.  The rain ALWAYS comes back.  And temperatures ALWAYS cool in the fall.  Even after the hottest summers we cool off.

We had a few heavy showers around the metro area earlier this afternoon but they are gone now.  I think we’ll be dry through Thursday, although a weak system might give us a sprinkle Wednesday night.  Otherwise our next wet system appears Friday.

It’s been much cooler this month due to an upper-level “dip” or trough in the jet stream.  You can see it’s still there on the GFS ensembles showing upper-level heights on Wednesday


The cool colors represent below average 500 millibar heights.  Then the same model for next Sunday shows the continuing cool pattern.


The ECMWF is similar and doesn’t show the upper-level trough dissipating until at least 10 days from now.  See the ECMWF ensembles showing the trough just starting to leave.


Very interesting since we were dominated by higher than average upper-level heights from late April through mid August.  I’ve always found it fascinating how a “switch can flip” and we go from one weather regime to another.  Typically it’s that late spring wet-to-dry switch.  But sometimes it goes the other way too and that appears to be the case for Autumn 2018.

Enjoy the 3-4 days of dry weather this week!

Chief Meteorologist Mark Nelsen

43 Responses to First Cool Month Since March; Feels Like October!

  1. Ken in Wood Village says:

    I was looking at the 12Z Euro and yea, it’s dry but I did see something close to the end of the run. If it comes true, we could be looking at a strong East wind event in the Gorge. If so, Crown Point anyone….lol 🙂

  2. Ken in Wood Village says:

    If we went by the CFS, we would have a very active October…lol. But that is a dream…lol

  3. Ken in Wood Village says:

    Wow, Mark’s 7 day forecast has us in the upper 70’s next week but another station has us in the upper 80’s. 🤔🤔

  4. Roland Derksen says:

    I’m enjoying these sunny days of very late summer this week. Looks like we’ll get rain tomorrow through Saturday, but next week autumn is going to get off to a really nice start.

  5. Jason Hougak says:

    Blog BUST

  6. Joshua Lake Oswego says:

    The 00z GFS is hot garbage. I have a feeling the ECMWF will trend more and more towards it and they will agree on something close to the GFS. Zero rain and close to 90 for at least a few days next week. The writing has been on the wall. Warmest temps in the country compared to normal. Lucky us.

    • Ken in Wood Village says:

      Joshua, you sound depressed? I always thought the ECMWF was more superior than the GFS? I also remember people telling me to never think what is 8 to 10 days out will actually happen. Until it’s out 5 days, then it probably will happen.

      Yea, I’m an optimist…lol. Let’s just see what the EURO says. I will cave when I see it 5 days out 🙂

      • Joshua Lake Oswego says:

        Just frustrated. I like your optimism.

        • Ken in Wood Village says:

          I know your frustration Joshua. I hear it from my family and friends when it rains. “I want the sun” or “I want it warmer” and what I like the most is “it’s been raining for days”. All I want to do is slap them. We have had more sunny and dry days than we have had rainy days. As you can see, I know your frustration.

          Have you looked at the 06Z GFS? It has gotten much wetter. It still has some warm days but it is still a week or more away and between now and then a lot can happen. Just cross your fingers and toes….lol 🙂 I like to see what the 12Z Euro has to say. 😉

        • I would call it more a lack of inverse wishcasting (i.e. pessimism, and very much a form of wishcasting). Forecasts 9 days out are not very reliable, and if the GFS and the Euro models disagree the Euro usually ends up being closer to what really happens.

  7. bg says:

    el Nino cometh

  8. bg says:

    El nino is developing

    • W7ENK says:

      Actually, no. Quite to the contrary, in fact.

      This El Niño died before it even got started…

      • bg says:

        El nino is forcasted to develop by this winter according to cpc and enso models , looks like a moderate event at that. warm and dry er then last winter is what im expecting ,mark should blog about this

        • W7ENK says:

          That’s really weird. ENSO 3.4 region SST’s have been in a steady decline since July, currently at +0.20C and dropping. I have no idea what sig the CPC is seeing that would drive them to that conclusion.

          Here’s the realtime weekly data from Australia BOM, updated 9/16.

          You can very clearly see what I’m talking about here.

          The CPC’s graph just looks bizarre.

          That projected bounce that was supposed to take place earlier this month that never happened? That’s not how these models actually work. There’s no practical reason why it would do that, so it doesn’t make any sense. I mean, c’mon, look at that!

          I’m forecasting ENSO Neutral coming up for at least the next 4 months.

          Oh, and don’t forget, the rules for an official El Niño/La Niña are:
          +/−0.5C for five consecutive months. That being the case, the clock hasn’t even started running yet. So technically — at this point — it would be impossible for this upcoming Winter to be classified as anything but ENSO Neutral.

          Rules are rules.

  9. Ken in Wood Village says:

    It’s so strange how the 00Z EURO changed so much. Now it doesn’t have a lot of rain. I think it could be a hiccup. What I do find interesting is the Low in the Gulf of Alaska at the end of the run. It’s huge and deep. At one point it’s 964mb. It looks like it wants to push any High pressure that’s in its way…lol. I like to see what the 12Z EURO does today.

    • Joshua Lake Oswego says:

      The low is going to be too far north now. It’s not just the ECMWF showing it. It has been shifting northward for a few runs. Looks like we might warm up quite a bit in 7-10 days too. We really, really could use more rain. What we got was nice, but the amount was heavily variable depending on location. We need a widepwread soaking. That doesn’t appear to be happening in the next 10 days and beyond.

      • Ken in Wood Village says:

        Yea, it’s looking drier and warmer but only to a point. I’m still holding onto hope the models will change again and we will get more rain. I still think we will have a breezy weekend.

      • Ken in Wood Village says:

        Well, the EURO brought back a little more rain. It’s a start…lol

    • W7ENK says:

      That’s called the “Aleutian Low.” It’s a regular and expected, fairly stationary feature of wintertime in the North Pacific. Don’t worry, sub 960mb is fairly run of the mill. Sub 945mb is when things really get stormy… about 1,200 miles out at sea. While that low often has a steering effect over the general jet stream/weather patterns across the Pacific based on where it shifts (East-West positioning), it won’t affect us directly.

      The only thing it means for us — definitively — is that our Summer has officially drawn to a close, and our 9-month rainy season has returned.

  10. W7ENK says:

    Dropped to 42 last night. I woke up shivering!

    Down to 57 inside. I’mma have to turn the heat on soon, methinks.

    • Paul D says:

      Do you not have any insulation? My low was 45 and my house doesn’t go below 67.

      • W7ENK says:

        I have a fairly small house. I also keep a couple windows open at night because I like to circulate some fresh air.

        • Ken in Wood Village says:

          Hehe, I do the same thing. I have to have circulation but I also like the room to be cool/cold. I have enough blankets on me but I need to have my face cold or I will wake up with a massive headache.

          I saw your other post about the El Niño. Thank you for posting the chat. What are your ideas of the upcoming fall/winter? I think we could have an active season but I think it maybe a little slow to start though. 🙂

        • W7ENK says:

          The optimist in me says this coming Winter falls into the well-established cycle of 5-year recursive big snow Winters. He’s cheerfully naïve, and probably wrong.

          The pessimist in me says this’ll be the year that ends up breaking that well-established cycle, and we’ll end up with a big fat goose egg for snowfall. He’s kind of an @$$hole, and also probably wrong.

          The realist in me says to keep my mouth shut, chances are it’ll probably be somewhere in between the two, so just wait and see what happens, take whatever we get and be happy. He’s also kind of an @$$hole, but he’s got a valid point, so… lol

        • JohnD says:

          ALWAYS enjoy Erik’s input!🙂

  11. Tyler Mode in Battle Ground says:

    39.3 in Battle Ground! Loving it!

  12. JERAT416 says:

    I think it’s time for me to take the AC out of the window

    • W7ENK says:


      I took mine out and put it back into storage DURING that thunderstorm last Wednesday. Nothing like (literally) waiting until the last minute! 😆

  13. Paul D says:

    We deserve the quick move to cooler weather after that brutal summer! Loving it!!!!

  14. Six consecutive nights in the 40s in The Dalles; this morning was the coolest at 42. And probably at least a couple more such nights ahead of us. I’m sure deciduous trees in the higher elevations are about to get triggered by the consistently chilly nights.

  15. Ken in Wood Village says:

    Ok, I’m wondering if other people see what I see for this Friday into Saturday on the 12Z EURO. It also showed it on the 00Z. And GO!!!

    • K says:

      I see it, it’s still there. GFS weakened and then strengthened it again.

      • Ken in Wood Village says:

        Hehe, I have been a little busy tonight but the last EURO model has some windy conditions for our area on Friday. Some wind could be over 30mph. Let’s see how the next couple runs do. 😉

  16. The summer weather was perfect for me this year, although my garden would be the first to argue that point. Sitting outside this morning with my coffee I noticed that first “crispness” of fall. Time to get out the rain gear and put away the shorts and spaghetti strap tanks for the year. Also time for every store and coffee shop to knock me over with the overwhelming scent of pumpkin spice. I love living in Oregon. 😁☕🌦️☔

  17. W7ENK says:

    Chilly last night, dropped down to 46. Bit of fog this morning, it felt like October.

  18. Ken in Wood Village says:

    Hmmm, the 00Z GFS looks much wetter then the past few runs. Maybe we could be starting to get into our wet season 🙂

  19. Ken in Wood Village says:

    Thank you for the update Mark. I said this a little over a month ago I think. I want to say the seasons were a little off. Where we started summer sooner around April or May. Now we are going to have a some what early fall.

    We could have a few days of clear sky’s and warmer temps (but I don’t think we will see a week of 80’s like we have seen in the past). I think the jet stream will become more active and storms will start dominating the Pacific instead of High pressure.

    I could be wrong but I think this is what could be happening.

    First 🙂

  20. halverbk says:

    Thanks as always for the great posts. After having hot and dry weather for so long, it does feel odd to switch so suddenly. Any thoughts about a connection between early starts and early ends to summer?

    • Roland Derksen says:

      It ‘s somewhat similar this year to what happened in 2015: The summer started early that year, it was hot and then we had a coolish unsettled September. Of course, what will happen in October may not necessarily go the same way.

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