UPDATE: 8/21/2018

At the 2:00 P.M. PDT observation, the Portland Airport had reached 91°, tying the all-time record for Number of Days ≥90° in a calendar year at 29 days (also in 2015). It would’ve occurred yesterday but the wildfire smoke was so thick (visibility was down to 3 to 6 miles on the hourly observations through the daylight hours) that it held temperatures well-below the predicted highs (83° maximum vs predicted 90° or so). Today, smoke was rather thick until some time between 11:00 A.M. and Noon, but now has appeared to push out, allowing the temperature to jump from 85° at the 11:00 A.M. observation to 91° at 2:00 P.M. Tomorrow is forecast to be about 90° to low 90s so would supersede the all-time record, reaching 30 days.  

The chart below has been updated accordingly.

ORIGINAL POST: 8/17/2018 

One day away, that’s all Portland Airport (PDX) is from tying its record of greatest number of days reaching or exceeding 90° in a calendar year. The current record of 29 days was set just 3 years ago in 2015, while 2018 currently sits at 28. The airport just missed tying the record on August 15th, when it reached 89°, which likely would have occurred had it not been for the Portland/Vancouver Metro Area’s saturating, heavy smoke, brought down on northerly winds from wildfires in British Columbia and Alberta. The smoke particulates likely reflected incoming solar radiation, suppressing the amount the temperature would have otherwise risen. With the current forecast calling for temperatures at or above 90° early next week, PDX is likely to tie or exceed the record.

The climatological period of record for PDX airport dates back to Nov. 1940. Below is a chart I’ve created showing the historical number of days with temperatures ≥90° for each full year from 1941 to year-to-date 2018. Take note of the increase in more recent years:

Portland-PDX_Days90_Data__Chart_1941-Present_Updated-2018-08-21

Click the link above for a larger version of the chart below.

Even when taking into account the longer-term downtown locations prior to 1941, the PDX record of 29 days with maximums ≥90° and current number of 28 days both exceed that data back to 1871 (that maximum being 17 days back in 1926, covering the period 1871-1940).  

Cover photo is of PDX, courtesy of travelandleisure.com