It was an unusually hot day at the NBCN weather station in Binningen. The minimum temperature was 12.6 °C, the maximum reached 29.0 °C, and the daily mean was 20.9 °C. Although the maximum fell just short of the 30 °C threshold that defines a hot day, the warmth was still notable for early September.

Looking at the last 30 days, the average air temperature was 22.63 °C, with a minimum of 10.3 °C and a maximum of 38.1 °C. During this period there were 26 summer days, 13 hot days, and one tropical night, where the temperature did not fall below 20 °C. This indicates a sustained spell of very warm conditions leading up to the day of interest.

For the current season, the day’s maximum temperature ranked 69th among the last 365 days, while the mean temperature ranked 78th. This places the day well within the warmest fifth of the past year, though not among the most extreme. In the context of all Septembers on record, the maximum temperature of 29.0 °C ranked 139th, and the mean temperature ranked 150th. The hottest September day ever recorded at this station was on 6 September 1949, with a maximum of 35.0 °C. The top five hottest September days are listed in Table 1, with the second hottest being 12 September 1947 at 34.7 °C, followed by 19 September 1947 at 34.5 °C, and then 5 September 1949 and 3 September 1962, both at 34.1 °C. The historic rank of the past day’s maximum temperature in September was 139th, confirming that while the day was warm, it was far from record-breaking for this month.