Record-breaking September heat today; PDX reaches 102°

Just a quick update for you tonight, along with lots of stats…it was HOT today!

Temperatures reached 102° in Portland today, the hottest September day since 1988 and the second hottest ever recorded for the month.
This is also the latest PDX has exceeded 100 degrees in the late summer/early fall season
It was also the second hottest day of the summer, surpassed only by the 104 degrees on July 9.
Note that the graph shows a classic late-season easterly wind event; temperatures are warmer in the western valleys than at lower elevations east of the Cascades
This is probably the last heatwave of the season. Only twice since September 10 have we experienced three days with temperatures above 32°C.

You can see that only the 105° day in September 1988 was hotter than today

By the way, it reached 100° four times in PDX this summer, which has happened to us in each of the last four summers!

Salem's weather records go back further, to the late 1800s. This is the first summer with 8 days of 100°C. Now I mentioned the second half of the summer, where the station at McNary Airport seems to get a little warm after a sensor replacement. But today's 101°C seems to be in good sync with surrounding stations.

Around 1pm I thought we wouldn't reach 100 because of the fire smoke overhead, but the layer was thin enough AND we had a relatively strong offshore current to overcome that smoke. We reached a pressure gradient of over 4 millibars from The Dalles to the metro area, pretty good for early September. Tomorrow will be different as no east winds are picking up anywhere in the metro area, just a persistent breeze in the western canyon. That tells me it will be cooler tomorrow, by at least 1-2 degrees, maybe a little more. Still, with afternoon temperatures between 90 and 35 degrees, this is another First Alert Weather Day from the western valleys to the canyon.

SOME GOOD NEWS

We've lowered our temperature forecast for the weekend. Increasing land currents and some high clouds mean we'll barely reach 90 degrees on Saturday, although higher dew points mean Saturday will be a humid day. Then strong ocean pressure will keep Sunday cloudy and highs as low as 80 degrees… much better! Back to normal.

Air quality at sunset is in the MODERATE category for most of us in the western valleys, which is pretty normal for a heat wave. Most of the smoke is in the atmosphere and is from fires in the central Cascades and central Oregon. Another day of east/southeast flow means we'll have another day of very smoky skies; the sun is again hazy and yellowish. HRRR smoke modeling suggests there may be a little more smoke settling from low elevations in the valleys. It's not bad, but probably in the UNHEALTHY category in a few isolated spots. The increasing onshore flow on Saturday should clear the air quite a bit.