DARRINGTON — The National Weather Service issued a red flag warning Friday in the western Cascades, including parts of Snohomish County, due to high fire danger.

Warm temperatures and low humidity led to “critical fire weather conditions,” the weather service wrote in a memo.

“In western Washington significant growth on existing fires takes place under such conditions,” the memo said.

The red flag warning applied to areas above 1,500 feet in the west and central Cascades. It remained in effect until 11 p.m. Friday.

Meanwhile, three lightning-cause wildfires continued to burn in the Mount Baker-Snoqualmie National Forest northeast of Darrington. The fires closed popular trails and campgrounds, as well as some roads, ahead of Labor Day weekend.

On Friday, a Level 1 “Ready” evacuation recommendation was issued for the Suiattle River valley, north of the river near the Skagit-Snohomish county line. The alert means residents should be ready to leave: “There is no immediate danger to your home, family or business, but the fire or other danger may be moving toward you.”

There was minimal risk to the town of Darrington and surrounding populated areas, according to the Darrington Fire Department. An incident management team was expected to set up base camp for fire operations at the Darrington Bluegrass Music Park.

The Lake Toketie fire held at about 90 acres Friday, while the Boulder Lake fire grew in size by about 10 percent in a day to 100 acres, according to the U.S. Forest Service. The Suiattle River fire held at 5 acres on Friday, with helicopter crews providing bucket drops. Crews were unable to directly access the larger fires due to steep terrain.

The Suiattle River fire was a priority due to proximity to private property, according to the Forest Service. Crews prepared to build a confinement line on Suiattle River Road should the fire move that way.

Suiattle River Road (Forest Road 26) is closed indefinitely. The following are also closed: Buck Creek campground, the Boulder Lake trail, the Huckleberry Mountain trail, the Buck Creek trail, the Green Mountain trail, the Downey Creek trail, the Suiattle River trail, the Sulphur Creek trail, the Sulphur Mountain trail and the Tenas Creek trail.

Contact the Darrington Ranger Station at 360-436-1155 for updated trail and road closures, or check the Forest Service’s website.

Thousands more acres were burning this week in the Cascades, in wildfires concentrated east of Mount Baker and west of Lake Wenatchee.

Skies may appear hazy due to wildfires across the state. Smoke impacts were expected to be minimal on Saturday, with southwesterly winds bringing in clean air, according to the Northwest Clean Air Agency.

An outdoor burn ban remained in place for all of Snohomish County, including cities, towns and unincorporated areas.

Jacqueline Allison: 425-339-3434; jacqueline.allison@heraldnet.com; Twitter: @jacq_allison.