A major heatwave is sweeping across Switzerland this week and throughout June 2026, with temperatures forecast to reach up to 38 degrees Celsius in Basel by Monday. Such a level would shatter the country’s all-time June temperature record, which has stood since 1947.
Meteorologists are warning that the heat building over the country from Wednesday, 18 June, could be historic. While most weather models project peak temperatures of 36–37°C in Basel, some outlier models show 38°C as possible by the end of the period, a figure that would comfortably exceed the existing national June record of 36.9°C, set in Basel-Binningen on 27 June 1947.
The heatwave arrives in two stages. Warm but not exceptional conditions are already building, with temperatures above 30°C expected in many parts of the country from mid-week. The heat then intensifies sharply: Meteonews is forecasting 31 to 35°C across most of Switzerland through the latter part of the week, with values pushing above 35°C locally by the weekend.
The extreme peak, potentially 38°C in Basel, is projected for Monday 22 June, though forecasters emphasise that most models converge on a somewhat lower but still record-threatening range of 36–37°C.
Zürich Airport and Lugano are also identified as locations where existing June records could be broken.
Read More: AI Jobs In Switzerland Hit Record 25,000 As Wage Premium For AI Skills Reaches 62%
Record That Survived Since 1947 Can Break: Switzerland Braces For Record-Breaking Heatwave
The current Swiss national June temperature record of 36.9°C, measured at Basel-Binningen on 27 June 1947, has proven remarkably resilient. In June 2022, it was equalled, but not beaten, when the station at Beznau AG also recorded 36.9°C. No June heatwave since has managed to surpass the post-war benchmark.
The last time Switzerland came close to a serious threat to the record was during the extraordinary European heatwave of 2003, a summer that produced Switzerland’s all-time temperature record of 40.5°C, recorded in Grono GR in August of that year. The June 2003 peak at Zürich-Kloten was 36°C.
The heat will not relent overnight. Meteorologists are warning of tropical nights defined as nights in which temperatures do not fall below 20°C, particularly in urban areas and the lower Rhine valley. For vulnerable groups including the elderly, the very young and those with chronic illness, sustained nighttime heat without recovery is medically significant. Switzerland’s federal public health authorities typically issue health advisories during heat alerts of this magnitude.
MeteoSwiss has issued heat warnings for affected regions; the most intense warnings, level 4, are expected for Basel and parts of Valais.
The increasing frequency with which Switzerland approaches and breaks June temperature records is consistent with the broader warming trend documented by MeteoSwiss. June 2022 was already recorded as the second-hottest June since measurements began in 1864. Climate scientists have long projected that extreme heat events once considered once-in-a-generation occurrences will become significantly more frequent as global temperatures rise.
