From June 2026 until late September 2026, North America was struck by a severe heatwave. Temperature records were tied or broken in several major cities across the United States and Canada. In Canada, the extreme heat brought large thunderstorms on July 1, Canada Day, which contributed to widespread flooding and thousands of homes being without power. In the United States, the extreme conditions strained public services, including public transit and the power grid, with delays and hundreds of thousands of homes without power for part of the heat wave.

The initial heat dome existed over the eastern United States and eastern Canada from June 28 until July 5; a peak of was recorded in Atlantic City, New Jersey, on July 4. A second heat dome is forming over the western half of the continent, with heat advisories currently in the southwest United States and Alaska. , there have been 70 deaths attributed to this heatwave.

This heatwave was concurrent with the FIFA World Cup, United States' Independence Day, and Canada Day, resulting in participants having to be in shade and hydrate frequently.

Background On June 11, the United States's National Weather Service found El Niño conditions were present, with the possibility of a "Super El Niño" as the year goes on. Climate scientists predict that with these 2026–2027 El Niño conditions, there would be higher temperatures and more of a likelihood of heat waves. CNN has stated that El Niño and human-caused climate change both contribute to the increased severity of heat waves.

Canada

Eastern Canada In Canada, Ontario and Quebec were under "orange" or "yellow" heat warnings, with temperatures expected to reach upwards of in some areas. Record high temperatures affected much of Ontario and Quebec on July 1, with a humidex of recorded in Ottawa. This extreme heat eventually led to large thunderstorms on July 1, and caused widespread flooding and storm damage across Ontario and Quebec, with a record of rain in Ottawa. Many Canada Day celebrations in the National Capital Region had to be cancelled. In Quebec, 100,000 homes supplied by Hydro-Québec lost power on July 2. By the next morning, 50,000 homes still were without power. During peak heat of with a humidex of , roughly 44,000 customers lost power in Halifax on July 3. On July 4, the Winterland area in Newfoundland set a daily high , surpassing the record set in 2005.

Ontario recorded the highest temperature since the 1936 North American heat wave on July 13. Armstrong set a new all-time high . Toronto recorded its hottest day since 2011 on July 14. Late on July 14, a cold front moved through southern Ontario bringing temperatures back down.

Western Canada With the heat dome in the eastern half of the country over, a second heat dome formed over much of the western United States and Canada. Seven communities set new records while four others had tied temperature records in Manitoba on July 12, the hottest being McCreary which set a new record of . On July 22, twelve communities in British Columbia broke daily heat records. Among them was Lytton, which recorded a temperature of .

Northern Canada Daily temperature records were set in Nunavut on July 4. Cambridge Bay broke the record set in 1930, recording . Kugaaruk set a temperature record of .

United States With an average temperature of , July 2026 was the hottest month in American history. The summer also finished as the hottest on record for the US.https://thehill.com/policy/energy-environment/6082122-summer-2026-hottest-on-record-noaa/ Eastern United States

Nearly half of the United States, 180 million people, were under a "major" or "extreme" heat risk by the National Weather Service starting on June 28. Temperatures were expected to reach between in many areas. On June 29, the heat index measured at O'Hare International Airport in Chicago was . The next night, the low temperature was just in La Crosse, Wisconsin, tying the all-time record warm low temperature. On July 2, ambient temperatures in New York City exceeded for the first time since 2012. Boston also reached that day, setting a new daily high temperature record and marking the 29th time the city reached the century mark. Amtrak reduced speeds for trains in the Northeast Corridor due to the extreme heat, and several trains were cancelled as well. SEPTA and NJ Transit also faced delays and cancellations due to the heat. The heat wave resulted in a fatality in Bethel Township, Pennsylvania. Additionally, over 17,000 customers lost electricity in New York City during the heat wave. PJM Interconnection, which serves power to 67 million people, got near, if not surpassed, its record for power demand, which was previously set in 2006 at 165 gigawatts. Surging electrical demand as a result of higher temperatures along with loads from data centers. The US Department of Energy ordered all electrical generators to run at full capacity, even backup units, for the second time this summer.

On July 3, following another day of record heat across New Jersey, including Atlantic City, severe thunderstorms in the state resulted in 250,000 power outages. This resulted in many people being unable to use air conditioning. The storms also amplified issues on NJ Transit from heat, forcing additional delays and suspensions.

The heat wave coincided with the US Independence Day on July 4, causing many celebration plans to be canceled, especially in the eastern portion of the country. Parades were canceled or delayed in Washington, DC, Philadelphia, and elsewhere.

Due to the heat wave during July 1–4, at least 44 heat-related fatalities were reported: 29 in New Jersey, 7 in Pennsylvania, 4 in Illinois, 3 in New York, and one in Mississippi. In addition, one heat-related death occurred in Mississippi on June 27.

From July 4–6, several rounds of severe thunderstorms moved across the United States that broke up the heat dome. However, those storms resulted in over 1.3 million power outages and four fatalities. The storms that broke the heat wave also possibly led to the largest hailstone in Connecticut state history.

Record heat returned to the region on July 15, when Lehigh Valley International Airport recorded a high temperature of , tying the daily record. Heating was limited on July 16, however, due to smoke from the 2026 Canadian wildfires.

During Tropical Storm Bertha, southern Louisiana was placed under both a tropical storm warning and extreme heat warning for the first time since 2005. Lake Charles recorded a heat index of .

A third major July heat dome began to impact the United States late in the month. Around 70 million were under heat advisories. Heat indexes of over extended from Minnesota to Mississippi. An all-time record high of was reported at the Rapid City Regional Airport, South Dakota, on July 26.

Extreme humidity surged into the Northeastern United States on August 7. New York City reached a dew point of , just one degree shy of the all-time record.

Western United States Following the advent of the heat dome in the eastern United States, a second heat dome started to form across the western and central United States on July 6. Phoenix, Arizona, reached a high of on July 6–8. Salt Lake City, Utah, recorded a new all-time high on July 12, reaching . Also in Utah, the temperature in Deseret reached an all-time high of . Additionally, local all-time records were set when Miles City, Montana, reached and Sheridan, Wyoming, reached .

The third major heat dome affected the Southwest in late July, with heat indexes of over in southern California and Nevada. Temperatures of up to were recorded. Across the west on August 1, there were 65 records that were either tied or set new records. In southern Nevada, emergency daytime cooling stations opened from August 6-11.

In early August, extreme heat in Colorado resulted in 72 hospitalizations.

Highest temperatures recorded CountryLocationTemperatureRecordDateAtlantic CityAll-time (tied)July 4Washington, D.C.DailyJuly 2PhiladelphiaDaily (tied)July 2BostonDailyJuly 2WilmingtonDailyJuly 2New York CityDaily (tied)July 2ToledoDailyJuly 1PhoenixNoneJuly 6–8Salt Lake CityAll-timeJuly 12DeseretAll-timeJuly 12BillingsAll-time*July 12Miles CityAll-timeJuly 12SheridanAll-timeJuly 12TorontoDailyJuly 1ArmstrongAll-timeJuly 13WinterlandDailyJuly 4KugaarukDailyJuly 4McCrearyDailyJuly 12LyttonDailyJuly 22

The National Weather Service and ABC News stated the measurement in Billings, Montana, on July 12, 2026, was an all-time heat record, despite a measurement in Billings on July 31, 1901.

See also

2026 European heatwaves – co-occurring heatwaves

References