CHICAGO—A prolonged heat wave continued to affect broad areas of the United States and parts of Canada on Sunday, prompting heat advisories and other weather warnings across multiple states as forecasters cautioned that high temperatures and unusually warm nights could increase health risks for millions of residents.
The U.S. National Weather Service (NWS) said dangerous heat and humidity were expected to persist across portions of the northern Plains, Upper Midwest and parts of the Mid-Atlantic, while local forecast offices maintained heat advisories and hazardous weather outlooks for numerous jurisdictions. The Weather Prediction Center said the hottest conditions were expected to gradually ease in some northern areas early next week as a cold front advances south and east.
Meteorologists warned that overnight temperatures would remain well above seasonal averages in many locations, limiting opportunities for people to recover from daytime heat. The combination of prolonged daytime heat and warm nights increases the risk of heat-related illnesses, particularly among older adults, young children, outdoor workers and people with underlying medical conditions.
The NWS urged residents in affected areas to stay hydrated, limit strenuous outdoor activities during the hottest parts of the day and seek air-conditioned environments where possible. Local emergency managers and public health agencies also encouraged people to check on vulnerable neighbors and family members.
The heat coincided with other weather hazards across North America. Heavy rainfall and flash flooding threatened parts of Texas and the southern Plains, while thunderstorms were forecast for sections of the Great Lakes, Mid-Atlantic and Southeast. Air quality alerts also remained in effect for parts of the Upper Midwest, Great Lakes and Northeast because of wildfire smoke transported from Canada.
In western Canada and parts of the northern United States, persistent hot and dry conditions continued to support wildfire activity. Officials warned that elevated temperatures, low humidity and gusty winds could contribute to increased fire danger in some regions.
Forecasts indicated that while some northern states could begin to see relief as cooler air moves in during the coming days, above-normal temperatures were expected to continue across several regions. The National Weather Service said it would continue updating heat advisories, excessive heat warnings and related forecasts as conditions evolve.
