In climate news, smoke from unprecedented Canadian wildfires darkened skies over much of the Midwestern United States Tuesday, triggering “very unhealthy” air quality warnings in Chicago, Detroit and Milwaukee. Forecasters predict winds will push the smoke further east today, bringing a return of hazardous air to New York and parts of the Northeast. This week the plume from worsening fires in Quebec and Ontario crossed the North Atlantic, bringing hazy skies to Spain and Portugal.

Meanwhile, there are warnings and advisories for excessive heat in effect again today in several Southwestern and Southern states. The Electric Reliability Council of Texas reports record power consumption amid a three-week-old heat wave that’s sent temperatures as high as 120 degrees Fahrenheit, or 49 degrees Celsius. The Texas Tribune reports at least nine prisoners, including two men in their thirties, have died of heart attacks or unknown causes this month in prisons lacking air conditioning. Science communicator Susan Joy Hassol says a collapse of Texas’s overstrained electrical grid right now would lead to widespread deaths.

Susan Joy Hassol: “The Texas grid appears to be very vulnerable to a heat event like this, because it doesn’t have the capacity to bring in power from other places. And this heat dome is really expanding. You know, they say 50 million people are already exposed to dangerous heat by this heat dome.”