Overview

• A late-June cold front plunged Eastern US readings by up to 40°F, bringing temperatures 10–15°F below normal before forecasts predict a swift rebound above average.
• The UK Health Security Agency has issued amber heat-health alerts from June 27 to July 1 for London, the East Midlands and other regions, forecasting peaks near 34°C and advising residents to close south-facing windows and curtains.
• Southern Europe’s first major summer heatwave is set to drive highs of 40–42°C in Portugal, Spain, Italy and Greece, prompting free access to public pools and bans on outdoor work during peak afternoon hours.
• Climate scientists link the surge in record highs over lows and rapid temperature swings to a weakened, wavier jet stream driven by human-induced warming, with U.S. daily high records nearly doubling daily lows so far this year.
• Authorities warn of significant strains on health and social care services, heightened wildfire risk and potential power system stresses as regions across North America and Europe confront extreme heat.