Fox News Weather Center

Record-Challenging Heat Wave Bakes Seattle and Portland, Oregon

The Northwest is dealing with yet another record-challenging heat wave to close out July. While relief will come next week, this heat wave will not be the last of the summer.

Intense heat will continue to bake the Northwest through Friday with a strong ridge of high pressure in control. Along the I-5 corridor from Medford to Portland to Seattle-Tacoma International Airport, the heat will challenge daily record highs.

Temperatures will crack the century mark throughout Oregon's Willamette Valley and many of the valley locations of the interior Northwest.

Widespread highs in the 90s F are expected along Washington's I-5 corridor. However, the Puget Sound will help to keep the heat at bay right along the water.

Downtown Seattle will enjoy the cooling effect from the Puget Sound, but more 90-degree days are expected at the Seattle-Tacoma International Airport (Sea-Tac/Seattle's official weather observation site).

Sea-Tac is set to break the record for the most 90-degree days in a year before the end of July. On Wednesday, this year tied the record of nine days from 1958.

Highs into Friday at Sea-Tac and throughout the Northwest will generally be on the order of 10 to 15 degrees above normal with a few locations pushing that value to 20 degrees.

Those seeking relief from the heat can head to coastal communities, where the air will be much more comfortable.

Otherwise, residents and visitors are urged to use extreme caution during this heat wave. Be sure to bring plenty of water, wear light clothing and avoid strenuous activities during the midday and afternoon hours (the hottest times of the day).

If air conditioning is not available and fans are not sufficient, seek out cooling centers. Remember never to leave children or pets in a sealed vehicle even for a short period of time.

The heat will persist but will not be as extreme this weekend along the I-5 corridor. For the interior Northwest, temperatures will remain just as intense as during the final days of July.

Northwest Short-Range Regional Weather Forecast

There is concern for the weekend to end with spotty afternoon thunderstorms sneaking into southern Oregon, heightening the risk of lightning sparking wildfires. Otherwise, dry weather will prevail and welcome rainfall will be absent as July transitions to August.

Further relief from the heat will come to the entire Northwest next week as the ridge breaks down, but that does not mean an end to additional heat waves.

"Heat will come back during the second week of August for about three to four days," stated AccuWeather Long Range Expert Paul Pastelok.