01:16 More Bad Air Days This Weekend in the West Ongoing wildfires in the West have caused major air quality issue. Meteorologist Danielle Banks explains the 3 big reasons the region will see bad air this weekend.

At a Glance An upper-level ridge of high pressure is bringing hot conditions to parts of the West.

Excessive heat is expected in portions of California this weekend.

The hot and dry conditions are fueling dozens of large wildfires burning in the West. Excessive heat is possible in parts of California this weekend, and hot and gusty conditions will continue to feed dozens of wildfires burning in the West.

A strong upper-level ridge of high pressure will be in place over the Southwest into this weekend, which will allow the heat to build in parts of the West and keep any rain at bay over the region.

<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/west_pattern_0727.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/west_pattern_0727.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/west_pattern_0727.jpg?v=ap&w=980&h=551 800w" > Upper-level ridge of high pressure will bring hot temperatures to parts of the West.

Temperatures will be 5 to 10 degrees above average for parts of the Northwest, California and the Southwest through the weekend.

Interior sections of California will see the most anomalous warmth this weekend. Widespread highs in the 95 to 110 range are expected there.

Low temperatures will also be warmer than average and will range from the upper 60s to the lower 80s in interior California, adding to the impact of the daytime heat.

This has prompted the National Weather Service to issue heat advisories in California from Bakersfield to Redding, where a prolonged period of hot conditions is under way.

An excessive heat warning was in place for Sunday across the southern part of California's Central Valley. Excessive heat warnings were also in place for Sunday across parts of Southern California, as well as the region around Phoenix, Arizona.

Heat-related illnesses are a concern in these areas, especially for the elderly, children, those with chronic ailments and those who spend a lot of time outdoors.

Although a few isolated daily high temperature records may be broken on Sunday, including Fresno, California, widespread records are not expected.

This pattern will also result in fewer showers and thunderstorms in the Southwest this weekend compared to last week. Most of the West will be dry with any storms mainly farther east in parts of Colorado and New Mexico.

Fire Concerns

The hot and dry conditions are not good news for firefighters battling the many large wildfires that have developed in the West.

In addition, gusty winds are expected in parts of the Northwest and Montana, adding to the fire concerns there.

In southern Oregon, the Milepost 97 fire, burning along steep, rocky terrain near Interstate 5, grew to about 14 square miles as of Saturday. Evacuation notices were issued for some homes and unhealthy levels of smoke are impacting the region.

"Communities near the fire have received elevated 'Level 2' warnings and are encouraged to evacuate," reported Oregon Live.

Close to 900 firefighters and 15 helicopters were battling the blaze.

Evacuations were also issued on Friday and expanded on Saturday for a wildfire near Helena, Montana . The North Hills Fire, about 10 miles north of Helena, had burned about 100 acres by Saturday.

"We are preparing for the worse-case scenario," Lewis and Clark County Sheriff Leo Dutton told the Independent Record.

Near Flagstaff, Arizona, the Museum Fire is burning near homes. It was about 46 percent contained as of Saturday evening and had burned over 3 square miles. No structures had burned and no injuries were reported.

The Sheep Fire near Idaho Falls, Idaho, grew quickly on Wednesday after a lightning strike. The fire burned more than 170 square miles and forced the evacuation of the nation's leading nuclear energy research lab. The Idaho National Lab said Thursday that operations were returning to normal .

Pattern Shift This Week

A shift in the pattern is expected next week as the upper-level high will slowly move from the Southwest into the southern Rockies.

As a result, the excessive heat will be reduced and temperatures will return to closer to average for late July.

(MORE: What We're Watching as July Ends)

NOAA's Climate Prediction Center extended outlook indicates much of the West will likely experience warmer-than-average temperatures into early August.

This will also be a more favorable pattern for monsoonal moisture to return to the Southwest and Four Corners region. However, the remainder of the West will generally be dry.

In its outlook issued on July 1, the National Interagency Fire Agency predicted that fire season would peak in August across much of the West. California is expected to re-enter fire season in October as the likelihood of offshore Santa Ana winds increases.