Similar red alerts were issued in France, Spain, and Italy, alongside warnings from authorities in Germany and Switzerland. In France, at least 18 people have died, and hundreds of schools were ordered to close as the national weather agency warned of a “prolonged and intense” heat wave. Temperatures in Bordeaux reached 42 degrees Celsius on Monday. Authorities noted that 54 regional administrative areas in France were under a red heat wave warning on Tuesday, a figure described as an unprecedented number. Mark Sidaway, deputy chief forecaster of the Met Office, stated that severe and significant impacts are expected, including health risks for many individuals beyond those typically most vulnerable to heat.
Concurrently, a stifling heat wave has peaked in San Diego County, with heat alerts in effect for all climate zones through Thursday. Inland temperatures reached triple digits on Wednesday, while coastal areas recorded highs in the 90s Fahrenheit. In Escondido, the hottest location in the county, a high of 112 degrees Fahrenheit shattered a record previously set in 1893. An unofficial reading at Gillespie Field airport in El Cajon hit 108 degrees Fahrenheit shortly before 1 p.m. on Wednesday. The National Weather Service issued an extreme heat warning for the desert regions through Friday at 8 p.m., while mountains are under a heat advisory through Thursday evening. Dangerous high temperatures in coastal and inland valleys are up to 15 degrees above average.
National-scale analysis indicates that human-caused climate change is fueling dangerous heat across much of the United States, with the heat wave spreading from the West toward the Midwest and South. Over two dozen states are forecast to experience temperatures above 100 degrees Fahrenheit (38 degrees Celsius) by July 28. Climate Shift Index levels of 5, the highest possible rating, are forecast for large areas of the country through that date. This level indicates that climate change made the extreme heat at least five times more likely. The analysis highlights the growing influence of anthropogenic factors on the frequency and intensity of such weather events.
Humidity is exacerbating conditions in the U.S. Southwest, with excessively high levels stemming from a mix of monsoonal moisture and heat rising from warmer-than-usual ocean temperatures. Much of the region remains muggy, and mountains saw afternoon thunderstorms earlier in the week. While the effects of recent tropical storms have faded, monsoonal flow has returned, preventing a break in humidity. Relief is expected to begin Thursday and Friday with lower humidity and cooler temperatures, but significantly cooler conditions are not likely before next Sunday. Seasonal temperatures are expected to continue into the following week.
