Millions of people across the Americas and Europe faced potentially life-threatening weather this weekend as a large heat dome settled over the central United States, a polar air mass brought record cold to Argentine Patagonia, and forecasters in Italy and the United Kingdom warned of a rapid return to extreme heat. No fatalities had been confirmed by late Saturday, but national meteorological services across four continents issued top-level alerts for heat, cold, snow and thunderstorms, affecting hundreds of millions of residents.

In the United States, the National Weather Service reported that a heat dome—a stagnant high-pressure system trapping hot air—would push temperatures to 10–15°F above normal across a swath from North Dakota to Texas, with readings surpassing 100°F (37.8°C). Advisories covered roughly 70 million people, and forecaster Bob Oravec warned that the system was likely to remain stationary through the week, compounding heat stress. Overnight lows were not expected to offer relief, raising health risks for vulnerable populations. Officials urged residents to seek air-conditioned spaces and stay hydrated.

In Argentina, the National Meteorological Service (SMN) maintained a red alert for extreme cold in Santa Cruz province, where temperatures were forecast to drop to -11°C in the cordillera region and could affect even healthy people. Snowfall warnings of orange and yellow levels stretched along the Andes from San Juan to Chubut, with accumulations of up to 150 cm in high areas and strong winds gusting to 90 km/h. The Paso Internacional Cristo Redentor and other mountain passes were closed. Meteorologists said the intensification of El Niño conditions in the equatorial Pacific was driving the dynamic, volatile weather, amplifying the seasonal cold outbreak.

In Europe, heavy rains were expected to sweep across Italy on Sunday before a rapid shift: Italian forecaster Lorenzo Tedici of iLMeteo.it projected the arrival of an African anticyclone from Wednesday, marking the fourth heatwave of the summer. Temperatures could reach 39°C in Milan and Rome, with peaks above 41–43°C in central and southern regions, and the hot spell was projected to persist until at least 10 August. In the United Kingdom, the Met Office warned of temperatures climbing to 35°C by midweek, with yellow heat health alerts in effect across much of England. Medical authorities cautioned that the elderly, children, and those with chronic conditions were at heightened risk of heat-related illness.

Across affected regions, emergency services remained on heightened alert. Meteorologists noted that while individual weather events are not unusual for late July, the simultaneous occurrence of such extremes across hemispheres reflected the influence of persistent large-scale atmospheric patterns and anomalously warm ocean surfaces. Authorities continued to monitor conditions and urged the public to follow official guidance as the hazards were expected to persist into the coming week.