Dangerous fire conditions in the Southwest are threatening to worsen blazes in Utah, Nevada and New Mexico, putting many communities on high alert this weekend.

The National Weather Service warned Saturday that gusty winds and dry air have created an “extremely critical risk” of fire weather — the agency’s highest threat level — across the Great Basin and Four Corners regions. Dry thunderstorms have brought the additional danger of frequent lightning, which can ignite fires, while parched vegetation helps flames spread and makes containment far more difficult.

The Cottonwood Fire in Beaver County, Utah, now stretches more than 92,000 acres and remains zero percent contained after five days. Low humidity and high winds accelerated its spread on Friday. Conditions are expected to ease somewhat Saturday, but the fire will likely continue growing as temperatures and winds climb in the afternoon.

Air quality in the Marysvale area is expected to reach unhealthy levels by the afternoon and evening. Sensitive groups — including children, pregnant women, the elderly, and those with heart or lung disease — should avoid outdoor physical activity.

Alyssa Mason, a spokesperson for the fire’s emergency management team, said there is no estimate yet for when the fire will be contained. Vegetation in the area has been drying since March, following record high temperatures and record low snowpack over the winter — conditions that contributed to extreme fire behavior, she said.

“Our plan of action has not changed. We are continuing to engage the fire where and when we can, with firefighter and public safety as our main priority,” Mason said in a statement.

The blaze damaged Eagle Point, a beloved ski resort, and forced evacuations earlier in the week. The resort’s owner wrote Wednesday on Facebook that it would be “closed for a considerable time to recover from the catastrophe.”

Several smaller fires in Utah have also prompted evacuations, road closures or power shutoffs. The Wild Goose Fire in Millard County ballooned overnight as fire crews worked to prevent the blaze from reaching a freeway; it now spans 1,000 acres. The Cherry fire in Juab County, exceeding 19,000 acres, is zero percent contained. The nearby Iron Fire, straddling Juab and Tooele counties, is 38% contained at more than 40,000 acres.

The National Weather Service Salt Lake City office issued a “particularly dangerous situation” red flag warning on Thursday, a designation reserved for exceptionally rare, life-threatening weather events and a first for the city. Wind gusts up to 50 miles per hour are expected Saturday.

Utah Gov. Spencer Cox has restricted fireworks statewide through July 5, limiting Fourth of July displays to select areas.

“Nothing about this decision was easy,” Cox said Thursday in a press release. “We are seeing fire behavior that even our most experienced firefighters say they’ve never witnessed before. This is a temporary measure for an extraordinary year.”

In Sandoval County, New Mexico, the McCauley Springs Fire has burned since Wednesday and remains zero percent contained at 722 acres. The Jemez Ranger District of Santa Fe National Forest, where the fire is active, has been temporarily closed to campers and visitors. A YMCA summer camp was evacuated Wednesday.

In Lincoln County, Nevada, The Grapevine Fire is zero percent contained and spans roughly 26,000 acres, forcing the temporary closure of Beaver Dam State Park on Thursday. The nearby Kane Springs Fire is approximately half contained at around 17,000 acres.

Arizona’s Pocket Fire, burning north of Sedona for more than a week, shows no sign of letting up.

“The winds are definitely working against us, and we expect to see a lot of the same effects that we saw yesterday today, if not accelerated — a little windier, a little gustier,” Clyde England, a member of the fire’s incident management team, said at a public briefing on Saturday.

Unless conditions improve significantly, Arizona Public Service said it would begin temporarily cutting power in high fire-risk areas around Flagstaff and the Grand Canyon as early as 10 a.m. local time Saturday. Roughly 8,000 customers would be affected.