It was an unusually hot day at the NBCN weather station in Binningen. The minimum temperature was 14.4 degrees Celsius, the maximum reached 29.2 degrees Celsius, and the daily mean was 20.5 degrees Celsius. Although the maximum fell just short of the 30-degree threshold that defines a hot day, the warmth was still notable for late September.

Looking at the last 30 days, the average air temperature was 18.89 degrees Celsius, with a minimum of 5.8 degrees and a maximum of 32.6 degrees. During this period there were 18 summer days, defined as days with a maximum of at least 25 degrees, and 4 hot days, defined as days with a maximum of at least 30 degrees. No tropical nights, where the temperature does not fall below 20 degrees, were recorded in the past month.

For the current season, the day of interest ranks 70th for maximum temperature and 85th for mean temperature among the last 365 days. This places it in the upper portion of the year but not among the most extreme days. In the historical record for September, the hottest day ever recorded at this station was 6 September 1949, with a maximum of 35.0 degrees Celsius. The second hottest was 12 September 1947 at 34.7 degrees, followed by 19 September 1947 at 34.5 degrees, and then 5 September 1949 and 3 September 1962, both at 34.1 degrees. These top five hottest September days are shown in Table 1.

For the specific date of 28 September 2026, the maximum temperature ranks 128th among all September days on record, and the mean temperature ranks 195th. This means that while the day was warm, it was far from the most extreme September heat ever observed at this station.