Wildfire Impact & Cross-Border Smoke
US and Canadian wildfire activity, and county-level US air quality
Nothing is isolated. Smoke from a wildfire doesn't check a map before it crosses a border -- in mid-July 2026, smoke from roughly 200 active Ontario wildfires plus fires in northeast Minnesota was pushed south into the US Great Lakes and Northeast, pushing air quality to "unhealthy" and "hazardous" readings in states with no fires of their own. The real evidence for that isn't a single number -- it's the pairing below: how much local wildfire activity a US state actually has, next to how bad its air quality actually got. Honest limitation: EPA's own official bulk air-quality dataset (AQS) has a real ~6-month processing lag -- its county-level data below is current through May 31, 2026, so it doesn't cover the July 2026 event yet. The table below it uses AirNow, a separate near-real-time EPA feed, to show the actual event directly.
The real event: worst PM2.5 readings, mid-July 2026
AirNow near-real-time AQI (not subject to EPA AQS's ~6-month bulk-processing lag) -- curated cities across the affected region plus a few unaffected control cities, so the contrast is real, not cherry-picked. Duluth, MN sits closest to the source fires in northeast Minnesota; Philadelphia shows the smoke reached well beyond the immediate Great Lakes region.
Reporting area State Date PM2.5 AQI Category
Duluth Area MN Jul 16, 2026 934 Hazardous
Duluth Area MN Jul 15, 2026 579 Hazardous
Southeast MI Jul 16, 2026 490 Hazardous
Milwaukee-Ozaukee WI Jul 16, 2026 355 Hazardous
Duluth Area MN Jul 17, 2026 301 Hazardous
Southeast MI Jul 17, 2026 282 Very Unhealthy
Milwaukee-Ozaukee WI Jul 17, 2026 252 Very Unhealthy
Philadelphia PA Jul 17, 2026 244 Very Unhealthy
Twin Cities MN Jul 16, 2026 231 Very Unhealthy
Southeast MI Jul 15, 2026 224 Very Unhealthy
Philadelphia PA Jul 16, 2026 214 Very Unhealthy
Western New York Region NY Jul 16, 2026 206 Very Unhealthy
Milwaukee-Ozaukee WI Jul 19, 2026 190 Unhealthy
New York City Region NY Jul 16, 2026 189 Unhealthy
Twin Cities MN Jul 15, 2026 187 Unhealthy
Western New York Region NY Jul 17, 2026 168 Unhealthy
Philadelphia PA Jul 18, 2026 167 Unhealthy
New York City Region NY Jul 18, 2026 158 Unhealthy
Milwaukee-Ozaukee WI Jul 18, 2026 158 Unhealthy
New York City Region NY Jul 17, 2026 155 Unhealthy
Western New York Region NY Jul 18, 2026 152 Unhealthy
New York City Region NY Jul 15, 2026 146 Unhealthy for Sensitive Groups
Hartford CT Jul 18, 2026 145 Unhealthy for Sensitive Groups
Hartford CT Jul 16, 2026 139 Unhealthy for Sensitive Groups
Southeast MI Jul 18, 2026 128 Unhealthy for Sensitive Groups
US wildfire activity, by state
NIFC/WFIGS, year-to-date. 5,408 total incidents on file.
State Incidents Acres burned
OR 262 2,198,442
NE 35 934,549
WA 390 775,583
UT 176 525,913
OK 136 425,561
ID 199 303,369
CO 91 278,268
CA 245 248,217
NV 206 238,688
TX 697 195,419
KS 37 158,461
AK 144 122,565
NM 81 108,530
MT 270 85,759
MN 368 76,915
AZ 116 59,569
GA 15 55,148
WY 220 50,413
FL 148 47,548
SD 135 45,314
MO 131 45,085
MS 147 26,294
LA 16 8,420
AL 35 6,129
WI 425 5,293
IA 13 4,642
ND 109 3,860
NC 19 3,390
AR 46 3,169
SC 17 3,146
MI 143 2,744
KY 37 2,524
MA 111 1,975
TN 12 990
VA 13 822
HI 1 478
GU 8 430
PA 24 358
ME 59 230
WV 3 192
IL 21 186
VT 3 126
NH 20 121
MX-TM 1 113
NY 2 97
MD 3 56
OH 5 42
NJ 6 32
RI 1 11
IN 2 8
DC 2 1
VI 2 0
US air quality, worst reading by state
EPA AQS, county-level PM2.5. A state with a high AQI here but little wildfire activity above is a real candidate for imported smoke rather than domestic fire -- compare the two tables directly.
State Worst AQI on file Worst PM2.5 (µg/m³) Days with data
Texas 259.0 183.8 90
South Carolina 189.0 110.1 151
Ohio 180.0 96.6 151
Georgia 175.0 89.9 120
Colorado 165.0 76.1 121
Nebraska 162.0 70.9 151
Alabama 154.0 59.6 90
Florida 153.0 57.8 90
Kansas 148.0 54.5 90
California 146.0 53.9 151
Arizona 143.0 52.5 90
Kentucky 131.0 47.5 90
New Mexico 127.0 46.0 90
Oregon 125.0 45.3 120
Michigan 124.0 45.0 90
New York 119.0 42.7 151
Arkansas 118.0 42.5 90
Washington 116.0 41.5 59
Oklahoma 105.0 37.3 120
Mississippi 102.0 35.8 151
Puerto Rico 102.0 36.0 86
Utah 100.0 35.3 151
Alaska 99.0 35.0 90
Missouri 99.0 34.8 90
Illinois 98.0 34.4 120
Iowa 98.0 34.4 151
New Jersey 97.0 33.9 90
Country Of Mexico 95.0 32.6 90
Indiana 94.0 32.3 151
Louisiana 92.0 31.0 151
Wisconsin 92.0 31.2 90
Massachusetts 90.0 29.8 69
Idaho 86.0 28.1 151
Pennsylvania 86.0 28.1 90
North Carolina 85.0 27.3 151
Tennessee 84.0 26.8 120
South Dakota 83.0 26.3 90
Rhode Island 82.0 26.0 90
Virginia 82.0 26.0 132
West Virginia 82.0 25.6 90
Maryland 80.0 24.9 90
Maine 79.0 24.1 151
District Of Columbia 77.0 23.0 151
Vermont 75.0 21.9 90
Wyoming 73.0 21.1 120
Nevada 71.0 20.0 120
New Hampshire 69.0 19.0 90
North Dakota 68.0 18.3 110
Hawaii 57.0 12.3 120
Montana 29.0 5.2 112
Canadian wildfire hotspot detections, by day
CWFIS (Natural Resources Canada), real-time satellite detection -- 674,418 total detections on file. This is the source-side evidence for the smoke: real fire activity in Canada, dated, ahead of when it reaches the US-side air-quality data above.
Date Hotspot detections
Jul 31, 2026 15,872
Jul 30, 2026 11,157
Jul 29, 2026 11,746
Jul 28, 2026 11,594
Jul 27, 2026 12,802
Jul 26, 2026 19,088
Jul 25, 2026 21,017
Jul 24, 2026 30,795
Jul 23, 2026 35,112
Jul 22, 2026 30,789
Jul 21, 2026 29,549
Jul 20, 2026 18,719
Jul 19, 2026 22,896
Jul 18, 2026 28,400
Jul 17, 2026 25,930
Jul 16, 2026 52,466
Jul 15, 2026 75,650
Jul 14, 2026 46,214
Jul 13, 2026 16,123
Jul 12, 2026 8,838
Jul 11, 2026 9,635
Jul 10, 2026 6,135
Jul 9, 2026 17,325
Jul 8, 2026 24,441
Jul 7, 2026 18,864
Jul 6, 2026 14,177
Jul 5, 2026 7,395
Jul 4, 2026 13,505
Jul 3, 2026 25,327
Jul 2, 2026 5,918
Jul 1, 2026 6,939
Sources: NIFC/WFIGS (US wildfire perimeters), CWFIS/Natural Resources Canada (wildfire hotspot detections), EPA AQS (county-level PM2.5). See Why we don't know what we know and Hurricane & Tropical Storm Impact for the related hazard-data work.