On Monday, much of western and central Montana woke up to unhealthy air quality, prompting warnings and forcing Missoula County Public Schools to cancel outdoor activities.

According to communications specialist Becky Goodrich, Missoula Parks and Recreation has also canceled all youth and adult sports activities for the day.

The Montana Department of Environmental Quality has issued air quality warnings for Broadwater, Cascade, Deer Lodge, Granite, Jefferson, Lake, Lewis and Clark, Mineral, Missoula, Powell, Ravalli, Sanders, Silver Bow and Teton counties. The warnings will remain in effect until Tuesday morning, when air quality will be reevaluated.

As of 10:30 a.m. Monday, the air quality was “unhealthy to very unhealthy” in the Missoula and Bitterroot valleys, and “unhealthy” in Seeley Lake and the Flathead Valley.

Brian Conlan, a meteorologist with the National Weather Service in Missoula, said the smoke is coming from nearby fires in the Bitterroot and from smoke blown in from Oregon.

“What you’re seeing now is the smoke has built up in the valleys overnight,” Conlan told the Missoulian.

Several fires in the Bitterroot brought ash to the region overnight. The Sharrott Creek Fire, Johnson Fire and Daly Creek Fire together burned more than 10,000 acres in the Bitterroot Valley.

“Many people in the Missoula and Bitterroot Valleys woke up to ash on their cars,” Benjamin Schmidt, an air quality expert in Missoula, said in an email update. He added that the ash most likely came from the Sharrott Creek Fire, but that fires in Idaho also impact our air quality.

Despite the unhealthy conditions, Conlan said a new weather pattern is expected to push most of the smoke out of the area. The National Weather Service is predicting a storm system could bring a quarter-inch of rain to the valleys on Wednesday, with up to 2 inches in the mountains and snow above 7,500 feet.

“The fires nearby may be causing smoke, but this storm will be good for most of them,” Conlan said.

State and local health officials recommend several measures to address poor air quality.

If air quality is unhealthy, people with respiratory or heart conditions, the elderly, and children should avoid prolonged exertion. Everyone else should limit prolonged exertion.

When air quality is unhealthy for sensitive groups, people with respiratory or heart conditions, the elderly, and children should limit prolonged exercise. When air quality is moderate, unusually sensitive people should consider reducing prolonged or strenuous exercise.