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  • Posted

9pm Tuesday...

Since I last posted, we've seen August give way to September. Labor Day Weekend has come and gone too, a nice "end to summer" with abundant sunshine but no hot weather.

Of course, meteorologically we just finished summer which runs from June to August. In Portland, Summer 2021 was just barely edged out by a slightly hotter Summer 2015. By 0.1 degree! Basically, it was tied with 2015 for hottest summer on record at PDX.

In Salem, Eugene, Medford, & Redmond it was the hottest on record. As I've mentioned many times, Salem's climate record is excellent, going back to the late 1800s. This summer was a scorcher!

This was our 9th consecutive warm/hot summer; of course, not all of those were "hot". Last year is a good example, just a bit warmer than average. 2012 was the last time we had a "cool" summer, mainly due to a very cool June. But 2015, 2018, & 2021 have been blazing hot. Portland has seen (so far) 24 days at/above 90 degrees. That's at the higher end, but we've seen more in 2015 and 2018.

Salem has seen 39 days that warm; a new all-time record there. Eugene also set a record...41 days at/above 90 degrees!

Of course, the drought continues... Portland has only seen .05" rain in just under 3 months. And the six-month period from early March through early September is the 2nd driest six-month stretch on record. Summer & early fall 1987 were slightly drier.

This means we are seeing another very dry "water year". By the way, a water year is a term used throughout the Western USA. Since most precipitation falls in the cold season (straddling two calendar years), it makes sense to look back at wet seasons separately, which means starting the "water year" on October 1st each year and ending September 30th. We've got three weeks left this year. Right now, it's the driest since the 2000-2001 drought Portland.

We haven't seen a wet year since 2016-17. Of course, we could easily pick up 2" rain the 2nd half of September, but even then it would be a much drier than normal year. Typically we get about 36" in Portland each year.

Do we have any rain ahead? Not really, at least nothing significant through mid-month. A weak system drops a few showers tonight, then mainly or all dry through at least next Tuesday/Wednesday. Take a look at the ECMWF ensemble forecast chart for the next two weeks. It shows 24 hour rainfall. Each thin horizontal line on upper part of chart shows one of the 51 ensemble members. Time goes from now (left) to two weeks out (right).

Notice almost no members produce .10" or more through the middle of next week, instilling high confidence that we'll be dry through the 15th. But you'll also notice around the 18th or so a lot of ensemble members say we could actually see rain. I'm not saying this is the case, but every few Septembers we get a big soaking the 2nd half of the month. In fact 3 of the past 4 Septembers we've picked up at least 2" rain during that time.

It would be wonderful (and mainly finish the fire season) if we could get 2" of rain in valleys plus 4" in mountains the last ten days of the month.

One more note, it's also obvious that we're making a turn toward more typical (cooler) September temperatures starting Thursday. The same morning ECMWF model ensembles show temperatures consistently in the 70-80 degree range the next 10+ days.

Summer is over...but warm early fall weather is here for awhile longer

Chief Meteorologist Mark Nelsen

  • Posted

9pm Sunday…

Hopefully you enjoyed this last weekend of August? It was quite a bit different than the cloudy/sprinkles stuff we saw last weekend. Portland hit 87 both days

A very interesting month…blazing hot first half, then near to below normal the 2nd half

At this moment, it’s still the hottest summer (June-August) in recorded history at PDX. BUT, it’s only slightly above Summer 2015. Add in two cool days (tomorrow and Tuesday), and I have a feeling it’ll be a tie for hottest summer in Portland. Salem’s records go back into the late 1800s and it’ll definitely end up as #1 hottest there.

The drought continues of course. The six months March-August are the driest on record at PDX, totally blowing away the previous years. Hard to believe we’ve seen less than 4″ of rain since the end of February!

I did check and find that is NOT the driest six months on record at PDX. There have been just a few other years in which May-October rainfall was less than 4″ as well. But we’ve never had a spring/summer dry combo like this.


We are in a typical late summer or early fall weather pattern now. That means we don’t stay in long warm/hot periods but not much rain either. Forget the air conditioning…nights have been in the 40s/50s much of the past week and that continues. Weak ridging overhead gave us the warm weekend, now a cool trough drifts through southern B.C. the next 2-3 days. You can see the dip in the flow Tuesday up around 18,000′

That’s on top of a major marine push in progress. Already at 8:30pm much of the metro area has dropped into the upper 60s. The westerly flow is also pushing all fire smoke east; notice the plumes coming off Cascade fires this evening are all headed into the eastern half of the state. This is the most active I’ve seen those fires in quite a few days.

More on fires in a minute

More onshore flow means highs only in the 70-75 degree range the next two days, but I don’t expect solid gray skies. Sun & clouds will mix.

Wednesday through Friday the trough moves east and atmosphere warms…we should be back in the 80s Thursday/Friday. It’s not a hot ridge of high pressure; no “heat dome”. Just an absence of any cool systems nearby. The Friday afternoon view


Models generally have some sort of upper-level trough swinging by around Sunday/Monday, but they are in great disagreement. Just taking a look at the ECMWF ensembles today, 21 of 51 members (a little under half) bring some real showers through Portland either Sunday or Monday. Of course that means more than half keep us dry through the holiday weekend. This chart shows each of those 51 members as one horizontal line on the upper half of the image. It’s 24 hour precipitation.

Anything with some color (not gray) means at least .10″. So details for next weekend are still to be resolved, but we know at least Saturday will be dry.


The cooldown and lack of thunderstorms the 2nd half of August has had a HUGE impact on fire weather. There has only been ONE big new fire in the state of Oregon in the past three weeks. That was the Fox Complex near Lakeview. No other new fire over 1,000 acres has ignited. Very good news. We still have 5 large fires (over 100 acres) burning in Oregon this evening, that’s down from around 10 a couple weeks ago. It’s 4 different complexes that started from lightning the first few days of August, plus the Jack Fire which began right around the 4th of July. That fire hasn’t seen much growth at all the last couple of weeks. But the other 4 keep burning steadily

The Bull Complex is an interesting one because it’s burning in a relatively small area between three of those mega-fires last September, maybe 5-8 miles north of Detroit.

That’s it for now…although I do have some “mixed emotions” news to share. Anne Campolongo has been a big part of our weather team for the past three years; the best weather team I’ve worked with. She’s one of the most professional people I know; smart meteorologist, friendly, great sense of humor, willing to learn, and really enjoys life. She came to us from Medford, just two years into a TV career after a meteorology degree. But now she moves on with 5 years experience in this business. Heading to the “big time” weather-wise! KCCI-TV in Des Moines, Iowa. That will be quite the severe-weather experience. Tornadoes, blizzards, damaging thunderstorms, etc… It’s also much closer to where she grew up in Ohio. So we’re sad she’s leaving, but happy she is headed to a good place.

Goodbye Anne!