Weather agencies on both sides of the Atlantic are signaling an abrupt shift toward autumn conditions this week, even as extreme heat lingers in the U.S. Southwest. In Europe, the UK Met Office says England, Wales and Northern Ireland will enjoy a warm, sunny bank-holiday Monday before a more unsettled pattern brings cloud, rain and building surf along western coasts from Tuesday. Mountain and coastal forecasts urge extra caution as waves strengthen during the holiday period. Across the Channel, forecasters cited by BFMTV expect a succession of thunderstorms from Tuesday through Thursday to sweep across southern and eastern France, knocking daytime temperatures as much as 10 °C below late-August norms. After mid-week, much of the country is predicted to settle into markedly cooler, more autumn-like weather. In the U.S. Great Lakes region, the National Weather Service has issued a Beach Hazard Statement through Monday evening for Indiana beaches, warning that 3-to-6-foot waves and rip currents on southern Lake Michigan will create dangerous swimming and small-craft conditions. Chicago reached a seasonable high near 74 °F on Sunday, and forecasters see dry, cooler weather persisting through mid-week. The Upper Midwest is also running cool. Highs in the Twin Cities barely reached the mid-60s Sunday, and some northern Minnesota counties could face frost advisories early Monday. Farther east, a strong cold front will cross the Mid-Atlantic and New England on Monday, bringing scattered thunderstorms and ushering in lower temperatures and humidity on Tuesday. Western states are trending cooler as well—Sacramento and Denver both expect a gradual decline in temperatures after Monday—yet the desert Southwest remains an outlier. Phoenix set a daily record warm low at 92 °F and is forecast to top out near 110 °F again on Sunday, prompting renewed heat-safety reminders from the local NWS office.