After a slow start, wildfire season has intensified in western Montana, with multiple blazes cropping up over the last week.

The state’s largest fire is the 510-acre Elder 1 incident southwest of Frenchtown in Rock Creek. Roughly 140 firefighters, including the Flathead Hotshots, were working to contain the perimeter of the lightning-caused fire. No structures were threatened, and no evacuations were ordered.

Northwest of Darby, the 105-acre North Fork Lost Horse Fire threatened more than 75 structures. Some roads were closed because of fire activity and heavy equipment operating in the rugged area of the Bitterroot Mountains.

The Silvertip Fire, about 30 miles northeast of Condon, had burned about 400 acres as of Tuesday. Just six firefighters were working the incident in a remote area of the Bob Marshall Wilderness.

Wildfire activity is more pronounced to the west, with more than 1.5 million acres already burned in eastern Washington and Oregon.

Smoke from those massive plumes continued to affect Montana on Tuesday. Air quality in Billings, Hamilton and Helena was deemed unhealthy for sensitive groups, while the Flathead Valley had moderate air quality. The haze was expected to linger into Wednesday for much of the western half of the state.

The weekend brings the potential for critical fire weather because of high temperatures approaching 100 degrees, along with low humidity and gusty winds. Areas along the Continental Divide could see gusts of up to 50 mph.

A moderate cooldown is expected by Sunday, with more seasonable highs in the 80s for the Flathead Valley.

“Unfortunately, there is no widespread precipitation in the forecast throughout the next week or so,” according to the Montana DEQ smoke forecast. “Smoky skies will remain a nearly constant theme into the first week of August.”