Often Wet, Yet Still Warm Overall
At the end of the year, the following annual values were obtained for 2023 from the Aachen-Hörn climate measuring station belonging to the RWTH Institute of Geography:
At 12.2 degrees Celsius, the year was once again one of the warmest years overall despite the cold and wet fall, in fact it was 2.5 Kelvin warmer than the average from 1961 to 1990 and 1.2 Kelvin warmer than the average from 1991 to 2020. With 1001 millimetres of precipitation, we expect an above-average annual total again after many dry years, namely 170 millimetres more precipitation than the normal value from 1961 to 1990 and 149 millimetres more than from 1991 to 2020. Although the fall was not very sunny over long stretches, the duration of sunshine was well above average, especially in June and September.
At 12.2 degrees Celsius, the average air temperature in 2023 corresponds to the penultimate record year of 2020 and it is 0.2 Kelvin below the previous record of 2022. The highest temperature of the year was 35.2 degrees Celsius, and the lowest was -4.9 degrees Celsius. There were 14 hot days with a maximum temperature greater than or equal to 30 degrees Celsius, which is six hot days more than the average for 1991 to 2020. As in the previous year, there were four days of permanent frost ("ice days" with a maximum temperature below 0°C). Only April was significantly colder (-1.6 Kelvin compared to the reference period 1991 to 2020). While the maximum temperatures were often only very moderate, the nights were often warmer than normal due to the frequent cloud cover. For example, the maximum temperature in November was 6.9 K colder and the minimum temperature 6.8 K warmer than normal.
Although it rained very frequently with a total of 220 days (21 days more than in the reference period 1991 to 2020, but on 26 out of 30 days in November alone), the precipitation total is well above average but by no means record-breaking. An annual total of 1001 millimetres has been reached or exceeded in the city of Aachen in six years since 1901, most recently in 1981 with 1013 millimetres. Other stations in the southwest of NRW also recorded high but - unlike in other parts of the state - no record values in 2023.