SmogRank / Episodes / United States
Minnesota and Wisconsin, United States, December 2023
For 1 day, on 22 December 2023, 15 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Saint Michael, Minnesota, United States: 31.9 µg/m³ on 22 December, about 4.8× its usual 6.7.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 15 in 1 country
Days 1 22 December 2023
Worst day 22 December 15 cities counted
Furthest above usual 5.0× Appleton
Day by day
Play 22 December 15 cities at twice their usual or more
Madison Waukesha Rochester South Milwaukee Zion Waterloo Holland Jenison Lansing Sault Ste. Marie Milwaukee Apple Valley Saint Paul Minneapolis Burnsville Eau Claire Blaine Grand Rapids Green Bay Shakopee Saint Cloud Superior Saint Michael Appleton Duluth 19 Dec 20 21 22 23 24 25 Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.
How it spread
Grand Rapids Grand Rapids, 19 December: 5.3 µg/m³, 0.7× usual Grand Rapids, 20 December: 15.3 µg/m³, 2.2× usual Grand Rapids, 21 December: 26.2 µg/m³, 3.7× usual Grand Rapids, 22 December: 30.4 µg/m³, 4.3× usual Grand Rapids, 23 December: 25.4 µg/m³, 3.6× usual Grand Rapids, 24 December: 18.2 µg/m³, 2.6× usual Grand Rapids, 25 December: 16.9 µg/m³, 2.4× usual Saint Michael Saint Michael, 19 December: 4.6 µg/m³, 0.7× usual Saint Michael, 20 December: 7.9 µg/m³, 1.2× usual Saint Michael, 21 December: 14.2 µg/m³, 2.1× usual Saint Michael, 22 December: 31.9 µg/m³, 4.8× usual Saint Michael, 23 December: 21.2 µg/m³, 3.2× usual Saint Michael, 24 December: 9.5 µg/m³, 1.4× usual Saint Michael, 25 December: 2.3 µg/m³, 0.3× usual Shakopee Shakopee, 19 December: 5.0 µg/m³, 0.7× usual Shakopee, 20 December: 9.5 µg/m³, 1.3× usual Shakopee, 21 December: 17.5 µg/m³, 2.4× usual Shakopee, 22 December: 31.7 µg/m³, 4.4× usual Shakopee, 23 December: 22.7 µg/m³, 3.2× usual Shakopee, 24 December: 9.2 µg/m³, 1.3× usual Shakopee, 25 December: 4.5 µg/m³, 0.6× usual Appleton Appleton, 19 December: 4.7 µg/m³, 0.8× usual Appleton, 20 December: 6.1 µg/m³, 1.0× usual Appleton, 21 December: 15.2 µg/m³, 2.5× usual Appleton, 22 December: 31.2 µg/m³, 5.0× usual Appleton, 23 December: 27.6 µg/m³, 4.5× usual Appleton, 24 December: 14.9 µg/m³, 2.4× usual Appleton, 25 December: 15.0 µg/m³, 2.4× usual Eau Claire Eau Claire, 19 December: 5.2 µg/m³, 0.7× usual Eau Claire, 20 December: 6.9 µg/m³, 1.0× usual Eau Claire, 21 December: 12.8 µg/m³, 1.8× usual Eau Claire, 22 December: 31.1 µg/m³, 4.3× usual Eau Claire, 23 December: 23.1 µg/m³, 3.2× usual Eau Claire, 24 December: 11.5 µg/m³, 1.6× usual Eau Claire, 25 December: 8.4 µg/m³, 1.2× usual Burnsville Burnsville, 19 December: 4.8 µg/m³, 0.6× usual Burnsville, 20 December: 8.4 µg/m³, 1.1× usual Burnsville, 21 December: 16.5 µg/m³, 2.2× usual Burnsville, 22 December: 30.7 µg/m³, 4.1× usual Burnsville, 23 December: 22.9 µg/m³, 3.1× usual Burnsville, 24 December: 11.8 µg/m³, 1.6× usual Burnsville, 25 December: 5.5 µg/m³, 0.7× usual Minneapolis Minneapolis, 19 December: 5.4 µg/m³, 0.7× usual Minneapolis, 20 December: 8.0 µg/m³, 1.1× usual Minneapolis, 21 December: 14.5 µg/m³, 1.9× usual Minneapolis, 22 December: 29.3 µg/m³, 3.9× usual Minneapolis, 23 December: 21.8 µg/m³, 2.9× usual Minneapolis, 24 December: 10.2 µg/m³, 1.3× usual Minneapolis, 25 December: 4.9 µg/m³, 0.6× usual Blaine Blaine, 19 December: 5.3 µg/m³, 0.8× usual Blaine, 20 December: 7.6 µg/m³, 1.1× usual Blaine, 21 December: 13.4 µg/m³, 2.0× usual Blaine, 22 December: 29.1 µg/m³, 4.3× usual Blaine, 23 December: 22.6 µg/m³, 3.3× usual Blaine, 24 December: 11.6 µg/m³, 1.7× usual Blaine, 25 December: 4.5 µg/m³, 0.7× usual Saint Paul Saint Paul, 19 December: 6.3 µg/m³, 0.8× usual Saint Paul, 20 December: 7.3 µg/m³, 1.0× usual Saint Paul, 21 December: 14.6 µg/m³, 1.9× usual Saint Paul, 22 December: 29.1 µg/m³, 3.9× usual Saint Paul, 23 December: 21.0 µg/m³, 2.8× usual Saint Paul, 24 December: 9.9 µg/m³, 1.3× usual Saint Paul, 25 December: 4.7 µg/m³, 0.6× usual Saint Cloud Saint Cloud, 19 December: 4.3 µg/m³, 0.7× usual Saint Cloud, 20 December: 7.1 µg/m³, 1.1× usual Saint Cloud, 21 December: 13.0 µg/m³, 2.0× usual Saint Cloud, 22 December: 28.8 µg/m³, 4.5× usual Saint Cloud, 23 December: 22.9 µg/m³, 3.6× usual Saint Cloud, 24 December: 9.0 µg/m³, 1.4× usual Saint Cloud, 25 December: 0.7 µg/m³, 0.1× usual Green Bay Green Bay, 19 December: 4.3 µg/m³, 0.7× usual Green Bay, 20 December: 6.5 µg/m³, 1.0× usual Green Bay, 21 December: 16.3 µg/m³, 2.5× usual Green Bay, 22 December: 28.1 µg/m³, 4.4× usual Green Bay, 23 December: 27.0 µg/m³, 4.2× usual Green Bay, 24 December: 13.1 µg/m³, 2.0× usual Green Bay, 25 December: 13.4 µg/m³, 2.1× usual Superior Superior, 19 December: 5.0 µg/m³, 0.9× usual Superior, 20 December: 3.1 µg/m³, 0.5× usual Superior, 21 December: 8.7 µg/m³, 1.5× usual Superior, 22 December: 28.0 µg/m³, 4.8× usual Superior, 23 December: 22.0 µg/m³, 3.8× usual Superior, 24 December: 11.6 µg/m³, 2.0× usual Superior, 25 December: 2.6 µg/m³, 0.4× usual Apple Valley Apple Valley, 19 December: 4.4 µg/m³, 0.6× usual Apple Valley, 20 December: 7.0 µg/m³, 1.0× usual Apple Valley, 21 December: 14.2 µg/m³, 2.1× usual Apple Valley, 22 December: 25.9 µg/m³, 3.8× usual Apple Valley, 23 December: 18.1 µg/m³, 2.7× usual Apple Valley, 24 December: 10.2 µg/m³, 1.5× usual Apple Valley, 25 December: 4.6 µg/m³, 0.7× usual Duluth Duluth, 19 December: 4.7 µg/m³, 0.9× usual Duluth, 20 December: 2.7 µg/m³, 0.5× usual Duluth, 21 December: 7.7 µg/m³, 1.5× usual Duluth, 22 December: 25.8 µg/m³, 5.0× usual Duluth, 23 December: 18.9 µg/m³, 3.6× usual Duluth, 24 December: 11.1 µg/m³, 2.1× usual Duluth, 25 December: 1.3 µg/m³, 0.3× usual Milwaukee Milwaukee, 19 December: 5.0 µg/m³, 0.7× usual Milwaukee, 20 December: 7.6 µg/m³, 1.0× usual Milwaukee, 21 December: 16.8 µg/m³, 2.3× usual Milwaukee, 22 December: 25.3 µg/m³, 3.5× usual Milwaukee, 23 December: 22.4 µg/m³, 3.1× usual Milwaukee, 24 December: 14.6 µg/m³, 2.0× usual Milwaukee, 25 December: 13.3 µg/m³, 1.8× usual 19 Dec 20 21 22 23 24 25 Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Appleton Wisconsin, United States 1 22 December 6.2 5.0× Duluth Minnesota, United States 1 22 December 5.2 5.0× Superior Wisconsin, United States 1 22 December 5.8 4.8× Saint Michael Minnesota, United States 1 22 December 6.7 4.8× Saint Cloud Minnesota, United States 1 22 December 6.4 4.5× Shakopee Minnesota, United States 1 22 December 7.2 4.4× Green Bay Wisconsin, United States 1 22 December 6.4 4.4× Eau Claire Wisconsin, United States 1 22 December 7.2 4.3× Grand Rapids Michigan, United States 1 22 December 7.1 4.3× Blaine Minnesota, United States 1 22 December 6.8 4.3× Burnsville Minnesota, United States 1 22 December 7.4 4.1× Saint Paul Minnesota, United States 1 22 December 7.5 3.9× Minneapolis Minnesota, United States 1 22 December 7.6 3.9× Apple Valley Minnesota, United States 1 22 December 6.8 3.8× Milwaukee Wisconsin, United States 1 22 December 7.3 3.5×
Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.
Against other episodes in the United States
Number 24 of 41 episodes in the United States since our records began, by cities reached.
North-eastern United States and Canada, June and July 2023 279 North-eastern United States and Canada, May and June 2023 260 North-eastern United States and Canada, July 2023 241 North-eastern United States and Canada, June 2023 161 North-western United States and Canada, August 2023 110 North-eastern United States and Canada, July 2023 75 Western United States, September 2023 61 South-eastern United States, October 2023 47 North-eastern United States, July 2023 46 North-western United States and Canada, May 2023 42 Western United States, December 2023 32 Northern United States, January 2023 32 Minnesota and Wisconsin, United States, December 2023 15 Bars: cities reached; colour: the level of the episode's highest daily reading. All 41 .
Use this page SmogRank, Minnesota and Wisconsin, United States, December 2023: 15 cities with PM2.5 at twice their usual or more, 22 December 2023, smogrank.com/episodes/2023-12-minnesota-and-wisconsin-united-states (accessed 2 October 2026).
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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms .
An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes . Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.
