Smoke from more than 700 wildfires burning across central Canada drifted over the Great Lakes and into the U.S. Northeast this week, pushing Minneapolis and Chicago to the top of global pollution rankings and prompting air-quality alerts in at least 10 states from Minnesota to Connecticut. Environment Canada issued similar warnings across Ontario, while New York state declared consecutive Air Quality Health Advisories for New York City and surrounding counties. Reduced visibility briefly disrupted flights in Boston, and public-health officials urged vulnerable residents to remain indoors and limit strenuous outdoor activity. The blanket of haze comes as a punishing heat wave fans new fires in the U.S. West. The Canyon Fire erupted Thursday afternoon near Piru on the Ventura–Los Angeles county line and expanded from roughly 30 acres to about 4,856 acres by nightfall, with containment still at zero. Authorities ordered some 4,200 residents in six Los Angeles County zones to evacuate and placed another 12,500 people under warning; four additional areas in Ventura County also face mandatory orders as helicopters and fixed-wing aircraft work to slow the flames. Fire crews are simultaneously battling the 99,232-acre Gifford Fire in San Luis Obispo and Santa Barbara counties, which remains only 15 % contained. The National Weather Service reported temperatures reaching 119 °F in parts of Southern California, leaving vegetation ‘ripe to burn,’ according to forecasters. Officials on both coasts advise keeping windows closed, running air conditioners or air purifiers and postponing outdoor plans until smoke and heat conditions ease.