Summer 2018: 2nd Hottest On Record In Portland

September 3, 2018

8pm Labor Day (Monday)

September has arrived and meteorological summer (June-August) has ended.  Sure, there will still be some very warm days and maybe even a 90 or two, but in general we’re done with the hot stuff.

Before summer began I think some of us were hoping it would just be an “average” summer after a series of hot summers.  That sure didn’t happen…it was a scorcher!


  • Weather was consistently warm to hot with few big swings toward extreme heat or cool.
  • But we didn’t break a single daily record high temperature in Portland!  Just one tie (95 on June 20th).  We only hit 100 once (July 15th), which is amazing considering it was the 2nd hottest summer on record.
  • Warm nights:  2 new record warm lows (June 12 & Aug 10) plus 3 tied record warm lows
  • Less morning cloud cover (marine air) than normal.  Seems like late July to mid August we hardly woke up to low clouds.
  • Summer “ended” somewhat abruptly after the 22nd of August.  Of course it didn’t really end but the heat suddenly disappeared.
  • Nelsen Pool Index: My above-ground pool peaked out at 85 degrees in late July and again during the hot spell in early August (same temp as last year).  But it has been very chilly and not really usable since that sudden change the last week of August.  Last year we were able to use it until the fire ashfall finished things off around September 4th.  Again, summer seems to have more abruptly “ended” this year.
  • We were dry, but nothing too unusual.  The very unusual part is the 1.5 month dry spell BEFORE SUMMER EVEN STARTED on June 1st!  That’s what has put us into a drought situation and is extremely stressful to vegetation/bushes/trees.
  • Where was the lightning?  I saw nighttime lightning once in late June  The next morning many of us woke up to a couple loud thunderstorms.  That was it!  What a boring summer, but that saved us from seeing lots more fire starts in the Cascades and possibly Coast Range.  We lucked out in the northern Oregon Cascades this year.

Here are the numbers,

MarkSummer WrapUp

Here’s how other cities around the region rank based on preliminary data:

Seattle:  2nd hottest
Olympia: 8th
Troutdale: 3rd
Salem:  4th
Roseburg: 6th
Medford: 8th
Astoria: 13th
Redmond: 6th
Pendleton: 24th

Note that for a bunch of these cities the top record-holding years are quite recent; we are living through a very warm period!  This has been the 5th consecutive warm/hot summer in the Portland metro area.

MarkSummer RecentYears

I can’t find a similar period within western Oregon in at least the past 100 years.  In the past there have always been cooler summers mixed in with the warm/hot summers, even during the warmer periods like late 1950s through mid 1960s.  Take a look at the past 100 years of Oregon climate zone #2, that includes most of the lowlands north of Eugene.  This is average summer temperature of all the weather stations combined, not including 2018.

download I’m not a climate scientist by any means of course.  But I wonder…

  1. Is the subtropical high that typically moves north in summer in the western USA wanting to build farther north lately, keeping us regularly warmer?  The western USA has warmed far more than east of the Rockies.  Many areas of the Midwest have seen little or no warming the past 100 years during summertime.
  2. If even without AGW (human-caused warming) we would have been in a warm period right now following that cool period around 2008-2011?  Basically is AGW piling extra heat on top of what was already a warm part of the climate cycle?
  3. If we don’t get much warmer the next 10 summers or so due to the Pacific ocean  remaining at almost the same temp.  There should be a limit to how much we can continue to warm with the same cold ocean sitting there giving us summertime marine pushes.
  4. Will we cool the next few years before heating up even more?  Or just stay the same before getting even hotter summers at some point in the future.

As for rain, of course it was dry, as it always is in summer.  But this year we saw less than 1/2 of our typical rainfall

Mark Summer Wrap Rain

It sure wasn’t a record dry June-August, but that follows an extremely dry 2nd half of spring.  The combo of May-August rainfall is the driest on record here.  We need a big soaking soon!

There you go…your Summer 2018 wrap up.  Hope you enjoyed the read and hopefully next year can be a bit more reasonable!

Chief Meteorologist Mark Nelsen