August 31, 2018

A Dry Summer

Western Washington's summers are nearly always quite dry, but this summer is unusually so.  

At SeaTac Airport, we are down about 2 inches from normal for the last 12 weeks (see below)

 And looking at the precipitation anomaly (difference from normal) over the past 90 days for WA state shows near normal precipitation over the Columbia Basin, but a dry western Washington, with the windward slopes of the Cascades being roughly 3-5 inches below normal.

To get some historical perspective, here is the May to July precipitation for Washington State since 1930.  This year was not a record low, but was one of the driest years during that period.  Overall, there has not been much a long-term trend in early summer precipitation, but we have had a drier than normal spell the last few years.

The good news is that the models are showing the return of light rain to our area.
For example, here is the forecast cumulative precipitation through next Friday using the UW WRF model.  Decent rain in British Columbia, which is very good--can help dampen down the fires.  And western Washington gets moistened, particularly the western side of the Cascades.

Regarding the holiday weekend, it should be dry through Sunday night, but then a upper level trough moves in.  So expect some light showers Monday AM that will be over by noon.

And then on Thursday a potent upper trough approaches (see below)...expect substantial cloudiness and some rain later on Thursday into Friday.  In short, normal conditions are back.  Heat waves and smoke are in our rear-view mirror.


  1. hopefully the forecast will change and summer will continue. there's plenty of time for rain and gloom...

  2. Looking at precip for Puget Sound Lowlands from June to Sept from 1895 to 2018 there was a gradual increase until 1970 and then a significant downtrend started, -.42"/decade,that appears to be accelerating.

  3. While Fall is my favorite season of the year, this is the first year where I am wholeheartedly waiting for the fall/winter rains.

  4. A mostly enjoyable summer. A few days that were too smoky, a few days that were too hot, but by in large, it was wonderful to be able to wear sandals out the door every morning for a hike around the property and not even have dew wet grass to deal with.

    My trees needed a few deep drinks to stay healthy, but otherwise my normal irrigation kept up and my younger evergreens grew like crazy this summer. Also many self-propogating (volunteers!) Cedars, Doug Fir and Maples popped up everywhere, along with three more Madronas (Arbutus) trees. As long as they had water, the trees seemed to really like this summer with a much higher than normal rate of propagation from natural cones/seeds. Never had so many volunteers on my property popping up in a single summer.

    There are always a few days in winter that suck, and a few in summer, but overall, I've loved living and eating on the deck since late June. Almost no mosquitos or flies this year (cause it was drier?) but more hummingbirds than usual. That's a win.

    I'll remember summer of 2018 fondly, presuming September doesn't go crazy. Which it rarely does.

  5. The past year I have lost two large hemlocks. Cisco indicated it has been a bad year for hemlocks. Today while driving to Duvall via Cherry Valley road, I counted double figures for caterpillar nests. I have never seen so many. Not complaining. I loved the warm and sometimes hot summers. The garden is great this year, especially the beans and peppers.

  6. A few rainy days during summer is not going to spoil anything. Seriously.

  7. It’s been extraordinarily dry here in Portland since mid-April. Only 1.5 inches of rain from April 15 through today (9/3): Don’t think there’s ever been so little rain over a 4 1/2 month period.

  8. seems like Cliff has everyone trained not to mention climate change; our kids are in a lot of trouble here and we are happy our peppers came in.


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