Record heat is expected throughout the Willamette Valley on Tuesday and possibly Wednesday.
A strong high-pressure system over the region is preventing cooler ocean air from moving inland.
A map of Portland's urban heat islands, the parts of the city that see hotter temperatures in heat waves.
Courtesy of Portland State University
Andy Bryant, a hydrologist with the National Weather Service in Portland, said the highs could reach 97 or 98 degrees in the Portland metro area.
“As you work your way down the Willamette Valley, you’ll run into highs right about 100," he said. "We’re looking for 100 in Salem, 101 in Eugene. It’s going to be a hot day throughout the state. Even at the coast there’s going to be some spots that are in the 80s.”
The National Weather Service reported Tuesday afternoon that the Portland airport had officially logged its 25th day this year that topped 90 degrees, a first for the area.
The Portland Airport @flypdx has officially set a record for the most 90F days in one calendar year at 25 in 2015. #pdxtst #orwx
— NWS Portland (@NWSPortland) August 18, 2015
Bryant said the heat has the potential to be dangerously hot, especially for children and pets.
“Heat stroke or just heat exhaustion can kind of creep up on you if you’re not paying attention," Bryant said. "We just encourage people to think about their plans for the day, make adjustments. If you can avoid outdoor activity during the late afternoon and early evening, that’s the best plan.”
Thursday is forecast to be much cooler, with highs in the 70s.