There’s a 25% Chance Portland Will Hit 100 Degrees This Weekend

Those odds get worse in certain neighborhoods at the eastern edge of the city.

Portland is nearing the one-year anniversary of the heat dome that brought 116-degree weather to the metro area and killed at least 59 residents of this city. And the weekend weather forecast is doing its best reenactment.

Temperatures this weekend will likely be in the 90s, but the National Weather Service says there’s a 25% chance temperatures reach 100 degrees in Portland. That’s a higher chance of topping 100 degrees than in surrounding areas of Oregon, where the likelihood is closer to 10%.

John Bumgardner, a meteorologist with the NWS’s Portland office, says the mercury will start rising Saturday morning and the heat wave will last through the weekend.

“We’ll start off warmer on Sunday, so it will be less hard for us to heat up,” Bumgardner tells WW. “That’s why we have a higher chance of getting to 100 on Sunday.”

Those odds get worse in certain neighborhoods at the eastern edge of the city. As WW reported last year, “heat islands” in outer Southeast and Northeast Portland can get as much as 25 degrees hotter than the leafy Northwest Hills.

“The urban heat island effect is pretty much always there,” Bumgardner says. “But it’s more of a big deal when it’s hotter, because every degree matters.”

The good news: Temperatures are expected to drop to the 50s and 60s at night, offering hours of reprieve. The lack of coolness at night during last summer’s heat wave exacerbated the crisis by trapping heat in the body and not allowing body temperatures to come down overnight. Elevated, persistent body temperature is the key driver of heat-related illness.

By Monday, meteorologists expect ocean air to flow into Portland. “That nice cool air will come in during the evening,” Bumgardner says. “It will feel better Monday night.”

Multnomah County has not opened any cooling shelters, but will extend the hours at three library branches on Saturday and Sunday evenings.

The expected heat wave not only converges with the anniversary of extreme temperatures. It also arrives as Portlanders are expected to take to the streets en masse to protest the U.S. Supreme Court decision in Dobbs v. Jackson that ends federal protection of abortion rights. City Commissioner Jo Ann Hardesty asked people to take precautions against the heat as they marched.

“My office will be donating some water bottles for rally attendees this evening,” she added.