Hot weather brings threat of smog to Vancouver-Portland area

A toasty ridge of high pressure will bake the Vancouver area through the weekend, with high temperatures in the mid to high 90s today and Sunday.

Forecasters say the heat wave will crest Monday, with a high near 100.

Vancouver recorded a high of 95 on Friday.

“We just have a big ridge of high pressure over us,” said Chris Collins, a meteorologist for the National Weather Service in Portland. “The onshore flow that we usually have each afternoon in the summer isn’t available right now, so we’re not getting any cooling from the ocean.”

If you’re hoping to beat the heat at the beach, think again.

Forecasters are looking for highs in the upper 80s or low 90s today on the north coast of Oregon, although marine air should seep in farther south to hold temperatures in the 70s around Newport, Ore.

Locally, the onset of hot weather prompted local air-quality authorities to issue an air pollution advisory for the Vancouver-Portland area through Monday.

The advisory calls on residents to voluntarily avoid unnecessary engine idling, and to refuel vehicles during cooler evening hours, limit driving, refrain from using gas-powered mowers and yard equipment, and put off painting and other activities that use aerosol sprays.

The forecast for Monday calls for a high of 99 degrees.

Air-quality authorities typically issue a warning for ground-level ozone, or smog, when forecasters predict temperatures above 90 degrees with gentle winds.

It forms when volatile organic compounds and nitrogen oxides mix together on warm, stagnant days.

“We generally have enough pollutants in the air for ozone to form,” said Paul -Mairose, chief engineer for the Southwest Clean Air Agency in Vancouver. “But in order to make (smog), you need pollution, the temperature and a little bit of mixing.”

The smog advisory is in effect today through Monday.