It was an unusually hot day at the NBCN weather station in Binningen. The minimum temperature was 13.5 °C, the maximum reached 28.6 °C, and the daily mean was 21.4 °C. Although the maximum did not reach the 30 °C threshold that defines a hot day, the mean temperature was notably high for the date.

Looking at the last 30 days, the average air temperature was 23.05 °C, with a minimum of 10.3 °C and a maximum of 38.1 °C. During this period there were 27 summer days, 15 hot days, and 2 tropical nights. A hot day is defined as one with a maximum temperature of at least 30 °C, while a tropical night is one in which the temperature does not fall below 20 °C.

For the current season, the day of interest had a maximum temperature rank of 69 and a mean temperature rank of 71 compared to the last 365 days. This places the day among the warmer days of the past year, though not at the very top.

In the historical record for September, the hottest day ever recorded at this station was 6 September 1949, with a maximum of 35.0 °C. The second hottest was 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. These five dates are shown in Table 1 as the top five hottest September days on record.

The maximum temperature of 28.6 °C on 3 September 2026 ranks 170th among all September days in the station’s history. Its mean temperature ranks 89th. While the day was warm, it did not approach the extreme heat of the historic September records.