PORTLAND, Ore. — The National Weather Service has issued an Excessive Heat Watch for most of the Northwest for Saturday through Monday, with the Portland-area likely seeing the season's first triple digit heat.
Starting Friday, temperatures will be 90 degrees or higher and could possibly continue through Tuesday or Wednesday of next week. This heat wave is on track to be historic for several reasons:
- The all-time hottest June temperature at PDX of 102 degrees will likely be broken.
- Portland's all-time hottest temperature on record for any time of year may be tied or broken. The record is 107 degrees and Portland has reached that three times over the years. The last time was August of 1981. Sunday's high temperature has a chance to reach or surpass that record with a forecasted 105 degrees or higher.
- The heat wave is expected to produce a total of 10 days in June reaching 90 degrees or hotter. The current record total for 90 degree days in June is nine days back in 2015.
- Many daily temperature records are likely to fall, including daytime highs and records for warm overnight lows. The current forecast shows low temperatures in the 70s Sunday and Monday mornings and both would set records. In fact, the all-time warmest low temperature at PDX in June is 71 degrees. Expect that record to fall.
It's unclear whether climate change is making heat waves in Portland more intense, according to Larry O’Neill, an Oregon State University Professor in the College of Earth, Ocean and Atmospheric Sciences.
“At least from this particular heat wave it’s an open question whether we can say with confidence if its definitively caused by climate change,” he said.
But - he said the weather is getting more extreme.
“If we look at a longer time period over a broader geographic scale, we do see many more high temperature records, for instance, being set versus low temperature extremes and that is definitely something climate change is primarily responsible for,” O’Neill said.
It's important to note that an unprecedented June heat wave does not guarantee a record hot summer, meaning the upcoming hot spell could be the worst the summer offers up.