A brief reprieve from hot, dry weather on Monday temporarily slowed the spread of Oregon's eight major wildfires. However, an ominous weather forecast loomed, even as the state welcomed assistance from external sources.

Oregon's largest wildfire, the Cow Valley Fire, located along the state's desolate eastern flank, had reached 132,528 acres by Monday. As of late Monday, the fire was reported to be 5% contained along its 163-mile perimeter, according to reports from the U.S. Forest Service, other federal agencies, and state fire officials.

The Cow Valley Fire achieved "megafire" status when it exceeded 100,000 acres sometime late Friday or early Saturday, as defined by the U.S. Interagency Fire Center. Early Monday, the high winds that had fueled the roaring flames and the consumption of dry, 3-foot-tall brush diminished. This temporary lull in the fire's expansion provided firefighters with a glimmer of hope for gaining control, according to a daily update from the agencies.

In response to the critical fire danger, Governor Tina Kotek declared an extended state of emergency in Oregon on Monday. On Friday, she had invoked the state's Emergency Conflagration Act to marshal additional resources to combat the Cow Valley Fire, which had ignited the previous day.

"Wildfires are active across Oregon and are growing at a concerning pace," Kotek stated on Monday. "Hot and windy conditions this weekend, including forecasted lightning in some areas, are threatening even larger wildfires."

South of the megafire lies the 2,275-acre Bonita Fire, which was reported to be 40% contained as of Monday, according to federal agencies. Both fires are managed by the Cow Valley Fire federal task force. Both incidents were classified as human-caused, though the exact mechanisms and responsible parties remain under investigation by state and federal authorities.

Governor Kotek's actions were supported by the deployment of two Oregon State Fire Marshal task forces assigned to the Cow Valley Fire, as well as assistance from two Washington state task forces, as stated by the fire marshal's office on Monday.

The weather provided some relief on Monday, as a high-pressure system that had been baking the West since early July shifted eastward, resulting in a temperature drop of 4 to 10 degrees in parts of Oregon. This change allowed the task forces to be reassigned to other fires, according to the fire marshal's office.

Additionally, evacuation readiness levels near the Cow Valley Fire were downgraded in some areas on Monday. However, the Westfall area remained under "get ready" status, advising residents to be prepared to evacuate as flames approached, as reported by the Malheur County Sheriff’s Office.

Resources from across the United States, including Alaska, Colorado, Florida, Georgia, Hawaii, Idaho, Montana, New Mexico, Oklahoma, and Texas, as well as from Canadian provinces Alberta, British Columbia, Saskatchewan, and the Yukon and Northwest Territories, were being allocated to Oregon's major fires, according to the fire marshal's office.

The second-largest fire in the state, the Falls Fire, located in Malheur National Forest about 5 miles southwest of Butte Falls, was measured at 64,225 acres on Monday, with no containment reported, according to federal agencies. Strong winds of up to 20 mph were anticipated Monday night, potentially exacerbating the fire's spread.

Mandatory evacuation orders were issued for parts of Grand and Harney counties. Authorities also closed down U.S. Highway 395 near the community of Riley on Monday evening due to the nearby fire activity.

By Monday, Oregon's eight wildfires had consumed approximately 250,000 acres, according to the National Interagency Fire Center. Four people have been injured and four structures have been destroyed in the Cow Valley Fire and the Falls Fire, as reported on the state's fire information dashboard.

The National Weather Service office in Portland forecasted a return of hotter temperatures this week, with temperatures expected to continue rising into the weekend. There was a 10% to 20% chance of lightning starting Tuesday. Inland areas of the state could experience high temperatures of 95 degrees by the weekend, the weather service reported.

A red flag warning was issued for Monday night, indicating dry conditions and potential lightning strikes for an area east of the coastline extending from the extreme northern reaches of California to Medford, Oregon.

The National Interagency Fire Center urged summer travelers to exercise caution and be mindful of fire safety.

"We cannot stop the hot weather and lightning storms, but we can do our part to be fire-wise when we are recreating, traveling, or staying home," the center stated in a daily report on Monday. "Take the time to find out the weather conditions and fire danger where you live and plan to vacation."

This detailed response underscores the critical situation in Oregon, the steps being taken to mitigate the fires, and the importance of public awareness and safety measures.