Wisconsin air quality index to reach 'unhealthy' level this weekend

Canadian wildfire smoke will impact all of Wisconsin throughout the weekend. The air quality index is expected to reach the Unhealthy for Sensitive Groups to Unhealthy level.

An air quality advisory is in effect for the entire state from 12 a.m. Saturday through 12 p.m. Monday.

Initial impacts are expected for northwestern counties starting as early as midnight Friday night, reaching central Wisconsin by early Saturday afternoon, and southeastern Wisconsin by late Saturday.

The heaviest smoke is anticipated for locations farther north, with periods of Very Unhealthy now possible. USG to Unhealthy AQI will be more likely for central and southeastern Wisconsin.

The lowest concentrations are expected across southwestern Wisconsin, where Moderate to USG AQI is more likely.

By Sunday, PM2.5 concentrations will be generally lower. However, USG to Unhealthy AQI will remain possible statewide, with higher concentrations more likely to the north.