Cooler, more seasonable air will take hold of the northwestern United States into the fourth week of August, but milder conditions may await heading into September.
However, a return to the extreme levels of heat earlier this month is unlikely.
“The extreme heat is over,” AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. “Ninety and 100-degree Fahrenheit heat in the Northwest is gone with temperatures now below normal through the week.”
The return of winds blowing in off the cool Pacific Ocean will hold temperatures in check, as well as keep air quality at much healthier levels.
“Temperatures will tend to run near to slightly below average in the Northwest through much of the fourth week of August,” AccuWeather Senior Meteorologist Jack Boston said.
Average highs along the Interstate-5 corridor from Seattle to Portland and Eugene, Oregon, range from the middle and upper 70s to the lower 80s F during the balance of August. Average highs over the interior hot spots trend downward toward the middle 80s.
The pattern will be ideal for those who had to limit time outdoors earlier in the month due to smoke and heat to resume outdoor activities.
Persistent dryness will keep the wildfire danger elevated despite the cooldown. Any unattended campfires and improperly discarded cigarettes and matches could trigger a new blaze over the abnormally dry ground.
As of Monday morning, Aug. 14, over two dozen large wildfires are burning across Washington, Oregon, Montana and Idaho, according to the National Interagency Fire Center.
“There won't be much rain except for a few showers in western Washington and western Oregon next week,” Boston said.
Average monthly precipitation begins to steadily increase across the Pacific Northwest heading into the fall following the driest month of the year, July. The most precipitation typically falls during the late fall and early winter months.
The cooler weather over the next week or two may not last heading into the end of the month.
“Latest indications show the pattern turning milder during late August into early September, but the heat should not be nearly as intense as what we saw earlier this month,” according to Boston.
Temperatures may return to the lower 80s in Seattle and come close to 90 in Portland under the warmer regime. Interior portions of the Northwest may soar back into the 90s. Still, intense record heat is expected to remain absent.
A heat wave for the record books
The heat wave that lasted from late July to early August certainly left its mark in the region’s weather history.
Daily record highs were set on multiple occasions in Portland, Eugene, Medford and The Dalles, Oregon, as temperatures soared 15 to 25 degrees above early August normals.
Medford, Oregon, came within 3 degrees of their all-time record high for any date with a temperature of 112 on Aug. 2.
Smoke from numerous wildfires in British Columbia and locally led to days of unhealthy air quality, further straining residents and visitors.