Exceptionally mild weather characterized Belgium on Tuesday, September 29, 2026. In Uccle, near Brussels, a new daily record was set, while a particularly mild night was forecast for the transition to Wednesday, September 30. However, available figures for the day’s maximum temperatures vary depending on the source.
A record announced in Uccle
RTBF reports a maximum temperature of 28.3°C on September 29th. Meanwhile, BX1, attributing its information to David Dehenauw, a meteorologist at the Royal Meteorological Institute (IRM), indicates 27.6°C, above the previous record of 27.3°C set in 2011.
The provisional climatological report from the Royal Meteorological Institute (RMI), available as of September 30, covers observations in Uccle only up to September 28. Therefore, it does not allow us to distinguish between these two values or officially confirm the record of September 29. The figure of 28.3°C should be considered with this caveat.
A mild night was expected
In its article published Tuesday, September 29 at 5:14 p.m., RTBF announced overnight lows between 17 and 19°C, with 19°C expected in Uccle. This was a forecast, not a temperature already observed. The publicly available report from the Royal Meteorological Institute (IRM), which I consulted, does not yet provide any information allowing me to confirm this result.
A September warmer than normal
In Uccle, the average temperature observed from September 1st to 28th reached 17.1°C, compared to a normal of 15.2°C, according to the Royal Meteorological Institute (RMI). This preliminary assessment places the month above seasonal averages, but is not sufficient to establish its final ranking.
A single weather record does not, on its own, demonstrate the effect of climate change. To assess climate evolution, one must rely on long-term observation series and statistical trends, rather than a single hot day.
Source: – Weather
Official source consulted: Royal Meteorological Institute of Belgium (IRM), provisional report for September 2026
Original article: See the original source
