Wildfire Smoke Map by State: Where Smoke Days Are Worst

From 2021 through 2025, North Dakota had more wildfire smoke than any other state, at an average of 49 smoke days per county per year. Minnesota was next at 47 and South Dakota at 43. The heaviest smoke exposure was across the northern Plains and Upper Midwest, while California averaged 15 and the typical US county logged 24 smoke days a year.

Most wildfire smoke maps show today's plumes and fire perimeters. They help when you're deciding whether to open a window this afternoon. They don't show where smoke keeps coming back. This page covers that: five years of satellite smoke data, averaged county by county and rolled up by state, so you can see how your state compares and how much it changes from one year to the next.

What counts as a smoke day

A smoke day comes from the NOAA Hazard Mapping System, which traces wildfire smoke plumes from satellite images. A county gets a smoke day when a plume of medium or heavy density sits over a point inside that county. Thin haze doesn't count.

Satellites see smoke from above, and smoke overhead doesn't always reach the ground. Treat smoke days as a measure of exposure risk. They show how often smoke passed over your area, which is not the same as how often people breathed it.

Ground-level air quality comes from a different source: EPA AirData annual AQI by county. A bad-air day is any day with AQI above 100, the level rated unhealthy for sensitive groups or worse. EPA monitors only some counties, 790 of them in this data, and a county's yearly average uses only years with at least 300 monitored days. In the median monitored county there were 2.4 bad-air days a year, against 24 smoke days a year in the median US county. Those medians come from different sets of counties, but the gap is still large, and it shows that most smoke overhead never pushed local air past the AQI 100 line.

Where wildfire smoke is the worst: the northern tier

Seven states averaged 39 or more smoke days per county, and all of them sit along the northern edge of the country or just south of it:

• North Dakota: 49 smoke days per county per year
• Minnesota: 47
• South Dakota: 43
• Iowa: 41
• Wisconsin: 41
• Montana: 40
• Michigan: 39

Missouri and Nebraska came next at 36, followed by Illinois at 33 and Kansas at 32. If you live anywhere from the Dakotas east to Michigan, you are in the part of the country where smoke passes overhead most often, even though few of those states are known for big local fires.

2023 was the peak year for the Midwest and East

The five-year averages hide one very bad year. In 2023, Minnesota logged 79 smoke days per county, Wisconsin 77, Michigan 76 and North Dakota 74. Each was the state's highest year in the data.

The Northeast had a bigger jump. Vermont went from 7 smoke days in 2022 to 57 in 2023, and Maine went from 7 to 50. New York and New Jersey each reached 58 in 2023, and Pennsylvania and Delaware each reached 56. In every one of those states, no other year came close. If 2023 is the year you remember breathing smoke, the data agrees with you.

The West swings harder from year to year

Western states have a different pattern: very high years followed by very quiet ones. In 2021, Wyoming logged 63 smoke days per county, the highest of any state that year, with South Dakota at 62 and Idaho at 60. Nevada had 58 smoke days in 2021 and 1 in 2023. Utah went from 46 to 3 over the same two years, and California went from 45 to 5.

That's why California's five-year average of 15 can mislead. A state with fires inside its borders can have one terrible season and then several clear ones, while states downwind keep collecting smoke from fires burning elsewhere. If you live in the West, plan around the bad years, not the average.

States with the least wildfire smoke

Hawaii recorded 0 smoke days in every year from 2021 through 2025. Alaska averaged 6, Arizona 7 and Florida 8. New Mexico averaged 11, though it had 29 in 2021. Arizona shows the same western pattern: 23 smoke days in 2021, then 4 or fewer in each later year.

Smoke days by state, 2021 through 2025

The full table is below, sorted by the five-year average. Each figure is the average number of smoke days per county in that state. Click a state to open its air quality page.

What this data can and cannot tell you

A state average combines every county in the state, so your own county may come in well above or below it. Your state's air quality page breaks the numbers down further.

A smoke day means a satellite saw a medium or heavy plume over your county. It doesn't tell you what was at street level or inside your home. The EPA bad-air day count is closer to what people breathed, but only 790 counties have monitors, so many readers live in a county with no ground measurement at all. Neither number tells you about the air in one specific apartment or house. Our methodology page explains how both measures are built.

What to do next

Check your state page. Start with your state in the table above and look at its worst year as well as its average. If your state had a year like Minnesota's 79 or Wyoming's 63, plan for that happening again.

Have a plan for smoke days. When a smoke forecast or the local AQI shows smoke reaching the ground, keep windows and doors closed. A portable air cleaner with a true HEPA filter, sized for the room you use most, removes fine particles from the air that circulates through it. If your home has central air, a higher-rated furnace filter catches more fine particles than a basic one.

Smoke is one indoor air question, not the only one. Radon is invisible and odorless, and our radon pages show the EPA radon zone for your county. Radon zones describe counties, not individual houses, so testing is the only way to know your home's level. If a test comes back high, you can get radon mitigation quotes from local installers. For drinking water results by city, start at our city directory or browse the guides.