PORTLAND, Ore. (KOIN) — Summer heat continues to build over the western half of the country. The source of the heat this week is from the high pressure system that brought triple-digit heat to the area last week.

Afternoon highs will skyrocket nearly 10 degrees from Wednesday to Thursday with 90-degree heat returning to the region. The average temperature this time of year in Portland is supposed to be in the low 80s.

Summer heat returns to Portland Thursday, August 24, 2023

Thankfully, this round of heat won’t get as warm as the record-breaking and deadly heat Portland saw last week. A low pressure system to the west will cap highs in the mid 90s through the weekend.

Warmer air works its way back into the Pacific Northwest from the Great Plains

This latest round of hot and dry weather is expected to increase the wildfire threat over the Cascades. A ‘Red Flag Warning‘ goes into effect at 11 a.m. Thursday morning and continues through Friday morning at 11 a.m.

Red Flag Warnings go into effect for the Cascades of Oregon and Washington Thursday morning and continue through Friday morning

One of the reasons why the fire threat is elevated is due to the threat of thunderstorms late Thursday evening. That thunderstorm chance will remain through Friday morning.

Thunderstorm chances grow late Thursday into Friday morning with lightning as the biggest threat to those over the mountains

None of these thunderstorms are expected to turn severe, but lightning posses the biggest threat to runners participating in Hood to Coast Friday morning.

Hood to Coast run could see a few thunderstorms for those running in the mountains Friday morning

Temperatures will remain hot and mostly dry through the weekend. The summer heat doesn’t give Portland a break until the middle of next week.

KOIN 6 Meteorologist Josh Cozart shares the warming trend Portland will see by the weekend

Cooler and wetter weather is expected to find its way back into the Pacific Northwest by the end of next week. Rain doesn’t look widespread or heavy, but the chance for moisture is a welcome sight seen in western Oregon and Washington.