Parts of the Rhine and Danube set record-low flows for September, according to the Copernicus Climate Change Service, and western Europe tied September 2023 as its warmest September on record at 2.51°C above average. Copernicus published both findings on 8 October 2026 in its monthly climate bulletin. The two facts belong together because heat, evaporation and a thin river are a familiar chain for barge operators and power stations.
EFAS Gauges and the Four Basins With Record-Low Flows
The bulletin singles out parts of the Rhine, Danube, Vistula and Garonne-Dordogne basins for record-low September river flows. Those are records for the month of September, in places within each basin, and not all-time minima for any river as a whole. Copernicus does not give a flow figure or a baseline period for the claim.
The Copernicus bulletin states that “Record-low September river flows occurred in parts of the Rhine, Danube, Vistula and Garonne-Dordogne” basins. The river data come from simulation rather than a single physical gauge. The bulletin says the river flow figures are calculated by the European Flood Awareness System, which Copernicus describes as the first operational pan-European flood forecasting and monitoring system. A modelled record is a statement about the system’s own archive of simulated flows, so a navigation gauge such as Kaub can read differently from a basin-wide model cell.
What a Low Rhine Does to Barges and Cruises
The freight consequences were already visible before September ended. Hapag-Lloyd told customers on 27 July that the Kaub gauge, the reference point for the Middle and Upper Rhine, stood at 31 centimetres, with the all-time low of 25 centimetres from October 2018 within reach. The shipping line warned that below roughly 30 centimetres at Kaub the Upper Rhine may effectively become non-navigable for inland vessels, and it set up rail and truck shuttles to Duisburg and Emmerich as a workaround.
By the last day of the month the trade site ShipUniverse reported the gauge at 1 centimetre at 05:00 and 0 centimetres at 13:00 on 30 September. The same report stressed that a zero reading does not mean a dry river, since the channel was still about 1.1 to 1.2 metres deep. It described a Dutch barge, Terra 2, grounding on a sandbar after leaving Düsseldorf with 168 Mercedes-Benz Sprinter vans, then returning to unload part of its cargo. That single account comes from one trade outlet and is not a Copernicus finding.
The mechanism is simple. A barge sits lower in the water when loaded, so when depth shrinks the operator carries less per trip, and the same cargo needs more sailings or shifts to rail and road. River cruise ships face the same channel constraints, which is why itineraries on both rivers are sensitive to a dry autumn.
The ERA5 Record Behind a Tie With 2023
The temperature claim rests on ERA5, the reanalysis produced by ECMWF for Copernicus. The ERA5 dataset is available from 1940 and is extended forward in time, so “warmest on record” here means warmest in the ERA5 record from 1940. The bulletin calls September 2026 the “joint warmest September on record for western Europe” and says it tied September 2023 at 2.51°C above average.
Copernicus defines western Europe as land between 11°W and 15°E and 37°N and 55°N, and it uses the 1991 to 2020 reference period elsewhere in the bulletin. For Europe as a whole, the average over land was 16.26°C, which is 1.54°C above the 1991 to 2020 average for the month. The western region ran well ahead of that continental figure.
A tie is a different claim from a new record. Two Septembers, 2023 and 2026, now share the top spot at the same anomaly, and the bulletin does not say that 2026 beat 2023 by any margin.
Global Warmth and the Missing Circulation Explanation
Globally, the bulletin ranks September 2026 as the second warmest on record, with a global-average surface air temperature of 16.27°C, which is 0.82°C above the 1991 to 2020 average and 1.63°C above the estimated 1850 to 1900 pre-industrial level. Carlo Buontempo, director of the Copernicus Climate Change Service, said “September was the second warmest on record globally.” He added that the world is in a new run of months above 1.5°C and that, with a strong El Niño still intensifying, the run is likely to last into 2027.
The bulletin does not, however, explain the European weather pattern behind the month. It names no blocking high, jet stream position or pressure anomaly for the Rhine and Danube regions, and El Niño is offered as context for the global outlook rather than as the cause of the dry European September. Attributing the low rivers to a specific circulation setup would go beyond what the source says.
What the record does establish is narrower and still consequential: a month of unusual warmth over western Europe, simulated flows at record September lows in parts of four river basins, and a freight system that was already struggling at Kaub before the month ended.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
More from Morning Overview
- Doctors warn a silent liver disease now affects one in three American adults
- The FBI told the rest of ShinyHunters to surrender after a 24-year-old was arrested
- Two passengers died at an Ohio toll plaza, and the NTSB now wants the cash lanes shut
- Long use of a common prostate pill is tied to a higher chance of glaucoma
