It’s The Hottest Summer Ever In Portland…Less than 2 Weeks to September!

You are living through what will likely be the hottest summer ever recorded in Portland.

Meteorological summer only has 10 days left (June-August).  As of now we’re running almost 3 degrees WARMER than the next closest contender (2009)!  In fact we would need to have an average high around 72 and low each night around 50 for the next 10 days to cool our average temperature down to 2009 levels. So…

2015 is going to end up as the hottest summer we’ve ever seen

Airport records go back to 1940; and downtown numbers go back to the late 1800s.  But the downtown observation was moved around quite a bit, including up high on roofs (not a good idea), so I don’t put a lot of faith in those earlier numbers in the summertime.  You can get a general idea if any other summers have been close by looking at the entire Climate Zone #2 here in Oregon; that’s all lower elevation locations between the Coast Range and Cascades.  Check out the NCDC data back over 100 years…the June-August average temperature:

Several things stick out:

1. Before 1958 there are no obvious contenders for really hot summers like we have now.
2. 1958 is a close call but likely cooler than this year.  Here in Portland, Summer 1958 was hot but nothing like this year.
3. As I mentioned in a blog post last September, our summers are definitely turning warmer.  Just since my teenage years (1980s), our summer weather has been warming about 0.5 degree per decade.  That’s 5 degrees/century IF that pace were to keep up! Obviously 35 years is a relatively short time period so you have to be careful.

Now before you get too excited about some sort of cataclysmic oven about to descend on the Pacific Northwest in the next few summers, take a look backward first.  Remember these 3 warm, then hot, summers follow 3 very cool and cloudy summers.  Remember how many of us (including me) wondered if this was some sort of change in our climate?  I even constructed a (small) greenhouse for growing tomatoes at my home since the garden was a part failure for two of those years.  Now it’s payback time.

We’ve seen a highly anomalous (unusual) pattern of high pressure lingering near/offshore the West Coast.  As regular readers of this blog know, this has been going on for 2+ years.  That includes the warm blob of ocean water offshore.  There is no reason to believe this is a “new normal” and no current research to suggest that.

So no, this is not the beginning of a sudden change caused by global warming and one should not make a (big) leap to a conclusion that all our future summers will be just like this one.    That said, there is a clear upward trend in that chart above.  With more warming anticipated globally over the next few decades, most likely there fewer very low dips in that chart and more high spots.  We’d better learn to adapt!

Chief Meteorologist Mark Nelsen