September 2025 Weather Report: Brussels Hoofdstedelijk Gewest
September 2025 brought notably drier and slightly cooler conditions to Brussels Hoofdstedelijk Gewest compared to historical averages. The month presented a mixed picture of early warmth followed by a significant cooling trend, with precipitation levels falling well below normal.
Temperature Overview
The average temperature for September reached 15.9 degrees Celsius, sitting 0.9 degrees below the normal value of 16.8 degrees. This modest cooling was driven by a dramatic temperature range throughout the month. The warmest conditions occurred early in the period, with Vorst recording a peak of 30.3 degrees on September 7th. In stark contrast, the coldest reading came late in the month when Oudergem dropped to 6.7 degrees on September 28th, illustrating the significant seasonal transition that took place during this period.
Precipitation Patterns
September proved to be considerably drier than average, with total precipitation reaching just 35.1 millimeters against a normal expectation of 72.3 millimeters. This represents a 51 percent deficit in rainfall. The wettest day occurred on September 13th in Ganshoren, which received 9.7 millimeters of precipitation. When examining precipitation by location, Oudergem accumulated the highest total at 41.3 millimeters for the entire month, yet this remained below average for the region.
Sunshine and Notable Events
Sunshine duration totaled 254.6 hours across the month, only marginally below the normal 263.8 hours, representing a 3 percent deficit. This relatively stable sunshine level helped offset some of the cooler temperatures experienced during the period. The combination of below-average rainfall and near-normal sunshine created conditions that were drier than typical for September in Brussels Hoofdstedelijk Gewest, with the month characterized by a transition from early summer warmth to autumn coolness.