Season Shows Milder Winter, Increased Precipitation Compared to Historical Averages

December 4, 2025

This season's weather patterns, characterized by a range of temperatures from -5.8°C to 29.1°C and significant precipitation on September 21, align closely with historical averages but show deviations in temperature extremes and precipitation, highlighting ongoing shifts in seasonal weather patterns. The season was warmer than the long-term average, with fewer summer and frost days compared to the last 20 years, underscoring the importance of continued monitoring and analysis.

The recent season has been characterized by a variety of weather patterns that offer interesting insights when compared to historical data. The average air temperature for this season was 10.9°C, with temperatures ranging from a low of -5.8°C on November 22 to a high of 29.1°C on September 20. This season also experienced a notably wet day on September 21, with precipitation reaching 45.2 mm, surpassing the 30 mm threshold that defines a particularly wet day.

In terms of sunshine and cloud cover, the mean global radiation was 97.6 W/m², and the average sunshine duration was 210 minutes per day. The cloud coverage was relatively high at 75.7%, accompanied by an average humidity of 81.9%. These figures suggest a season with limited sunshine and a generally humid atmosphere.

The season saw six summer days, defined by temperatures exceeding 25°C, but no hot days where temperatures surpassed 30°C. There were seven frost days and one ice day, indicating a mild winter presence within the season.

Comparing these figures to the last 20 years, the average temperature of 11.4°C was slightly higher than this season's 10.9°C. Historically, the coldest temperature in the last 20 years was -8.8°C, and the warmest was 32.1°C, both more extreme than this season's values. The recent wettest day with 45.2 mm of rain was significant, though not unprecedented when considering historical records.

Looking at the long-term data since 1865, the average temperature for this season was 10°C, suggesting that the recent season was warmer than the long-term average. The historical extremes include a minimum temperature of -11°C and a maximum of 35°C, indicating that while this season had notable temperature events, they were not record-breaking.

The number of summer days and frost days this season was lower than the 20-year average of 158 summer days and 115 frost days, reflecting a less intense seasonal variation. The single ice day this season is also below the 20-year average of five ice days, highlighting a milder winter component.

Overall, this season's weather patterns align closely with historical averages but show some deviations, particularly in terms of precipitation and temperature extremes. These variations provide valuable insights into the ongoing shifts in seasonal weather patterns, emphasizing the importance of continued monitoring and analysis.


Table 1: Comparison of Fall 2025 with Historic Seasons: Since 2000 and Before 2000
Parameter Current Season Since 2000 Before 2000
Max. Temp [°C] 29.1 32.1 35.0
Min. Temp [°C] -5.8 -8.8 -11.0
Avg. Temp [°C] 10.9 11.3 9.7
Avg Precipitation [mm] 316.5 206.4 195.3
Avg. Sunshine duration [h] 319.0 357.9 287.7
Avg. Summerdays (>=25°C) 6.0 7.0 4.0
Avg. Heatdays (>=30°C) 0.0 0.0 0.0
Max. consecutive days >25°C 0.0 5.0 10.0

Figure 1: Historic Average, Minimum and Maximum Fall Temperatures [°C]

Data source: Opendata Basel-Stadt

🤖 This text was generated with the assistance of AI. All quantitative statements are derived directly from the dataset listed under Data Source.