The smoke of wildfires in the western U.S. hung heavy in the air in North Platte Wednesday afternoon, heavy enough to cover the setting sun.

The situation may continue through Friday, depending on weather patterns, the Nebraska Department of Health and Human Services said.

The smoky air could be unhealthy for sensitive groups, the state health department said. Conditions are expected to move back to the green category (no impacts) by Saturday.

Unusually sensitive groups should consider limiting prolonged outdoor exertion.

Smoke advisories are based on data provided by state department of environment and energy, the National Weather Service, and air quality monitors in Scottsbluff, Grand Island, Lincoln, Omaha and Bellevue.

For an hourly update on air quality across Nebraska visit .