September 2025 brought cooler and drier conditions to South Holland compared to historical averages. The month presented a mixed weather pattern with early warmth giving way to autumn chill, while precipitation remained notably below normal levels.
Temperature Overview
The province experienced an average temperature of 15.3 degrees Celsius, running 1.3 degrees below the normal value of 16.6 degrees. This cooler-than-average month saw significant temperature variation across the region. The warmest day occurred on September 7 in Goeree-Overflakkee, where temperatures reached 28.6 degrees Celsius, marking the peak of early autumn warmth. In stark contrast, the coldest reading came on September 28 in Gouda, where temperatures dropped to just 6.7 degrees Celsius, reflecting the transition into late autumn conditions.
Precipitation Patterns
September proved to be considerably drier than average, with total precipitation reaching only 55.6 millimeters against a normal value of 80.7 millimeters. This represents a 31 percent deficit in rainfall. The wettest day occurred on September 15 in Den Haag, when 19.5 millimeters of rain fell. Across the province, Noordwijk recorded the highest total precipitation with 80.8 millimeters, making it the wettest location during the month.
Sunshine and Extremes
Sunshine hours totaled 276 hours, nearly matching the normal value of 278.3 hours with only a 1 percent anomaly. This near-normal sunshine duration helped offset some of the cooler temperatures experienced throughout the month. The temperature range across South Holland was substantial, spanning from the 28.6-degree peak in Goeree-Overflakkee to the 6.7-degree minimum in Gouda, illustrating the diverse microclimatic conditions present across the province during this transitional autumn period.