Météo-France files complaint after detecting abnormal temperature spikes of 3°C in seconds at Charles de Gaulle Airport; bets placed on Polymarket totaled US$1,4 million on the suspicious days. Bobigny Public Prosecutor’s Office investigates equipment tampering that benefited bettors (Photo: Press Release)
The French meteorological service Météo-France has filed a complaint with the police and the Public Prosecutor’s Office alleging possible tampering with temperature measuring equipment at Charles de Gaulle International Airport. The investigation is looking into whether the alterations to the records, verified on April 6th and 15th, were intended to influence bets on the platform. polymarketThe Bobigny Public Prosecutor’s Office is conducting the investigation.
Ruben Hallali, CEO of the climate risk management company Sereno, had programmed alerts for extreme weather variations on his cell phone. In early April, he received a notification indicating an increase of approximately 3°C in seconds in the temperature at Charles de Gaulle International Airport. The phenomenon repeated itself nine days later, according to information released by Estadão.
Anomaly detection
Hallali observed that the temperature increases occurred at a single weather station, in the early evening. Experts and participants in the French meteorological forum Infoclimat also identified irregularities in the data. They initiated analyses to determine the origin of the anomalies.
After the first episode, theories emerged including a possible user error. After the second peak, commentators focused on unusual bets on… polymarket.
Timeline of the episodes
On April 6th, the temperature at Charles de Gaulle Airport rose from 18°C to 21°C at 19 PM. It dropped slowly over the following hour, according to data from Météo-France.
On April 15th, the recorded temperature jumped from 16°C at 21 PM to 22°C at 21:30 PM. It returned to 16°C half an hour later. In both cases, the peaks defined the maximum temperature of the day, an indicator used as a basis for some predictions. polymarket.
Météo-France filed a formal complaint following the second incident.
Hypothesis investigated
Authorities are investigating whether the weather sensor was deliberately manipulated to influence betting results on the daily maximum temperature in Paris. Forecast markets such as polymarket e Kalshi They allow users to bet on the outcome of virtually any event.
Weather betting is becoming an increasingly popular area. Speculators can place real-time bets on temperature readings, rainfall totals, the number of Atlantic hurricanes in a year, and other phenomena. With the rise in betting, the temptation to tamper with instruments used to generate weather readings has grown, in the hope of manipulating a profitable outcome.
Hallali observed that the timing of the peaks was perfect for someone to unexpectedly profit on the betting site. polymarket.
Financial movement
Bets on the daily maximum temperature in Paris totaled nearly US$1,4 million (R$7 million) on the two suspicious days. Some bettors received thousands of reais in payouts, according to company data.
The amounts wagered on April 6th and 15th were hundreds of thousands of dollars higher than on typical days this month.
Involved in the case
The case involves Météo-France, which identified the irregularities and alerted the authorities. Ruben Hallali, from the company Sereno, was one of the first to detect the anomalies.
Bettors in polymarket Those who placed bets on the daily maximum temperature in Paris on the days in question benefited from the fluctuations.
Laurent Becler, spokesperson for Météo-France, confirmed that the service contacted the police after noticing discrepancies in the temperature data. He declined to comment further on the case, stating that it is under investigation.
Change of data source
Temperature fluctuations were recorded at Charles de Gaulle International Airport in Paris. The airport is the largest in the country.
Following the filing of the complaint by Météo-France, the polymarket The platform has changed its data source. It has started using temperatures recorded at Paris-Le Bourget airport, also near the French capital, according to recent bets available on the site.
Points not clarified
The investigation has not yet determined whether there was intentional tampering with the weather sensor. It has not identified any possible parties responsible for the manipulation. It is also not confirmed whether the unusual bets on… polymarket They are directly related to the recorded temperature fluctuations.
The investigation conducted by the Bobigny Public Prosecutor’s Office has not released information about identified suspects or confirmed methods of tampering. Representatives of Charles de Gaulle Airport only confirmed that the case is under investigation. They did not provide further details.
Airport police also declined to comment on specific aspects of the investigation. The Bobigny Public Prosecutor’s Office did not answer questions about the progress of the investigation. It only stated that no complaint had been filed against the platform. polymarket.
There is no official confirmation as to what type of device or method was used to alter the temperature readings.
Next Steps
French police and prosecutors will conduct investigations to determine if the sensor was tampered with. They will seek to identify any individuals responsible. Météo-France will provide the technical evidence that prompted the complaint.
O polymarket It has already implemented a change in its methodology. It has replaced the Charles de Gaulle Airport data source with Paris-Le Bourget Airport for temperature predictions in Paris. This change was adopted after Météo-France filed a formal complaint.
The investigation continues under the responsibility of the Bobigny Public Prosecutor’s Office. There is no set deadline for its conclusion or the release of results.
Risks to airport security
Temperature data is used in a number of calculations at airports. It helps determine the correct takeoff distance, the rate of climb, and whether crews need to apply anti-icing treatment to aircraft. It’s crucial for airport safety, Hallali said.
Experts warn that tampering with meteorological instruments can have dangerous side effects. It can degrade the information that underpins the safety of air travel.
Theories about the method used
Several theories have been presented. online Regarding how the measuring instruments could have been tampered with, several hypotheses have been raised, including the use of a hairdryer or lighter to heat the temperature sensors.
Hallali assessed that the accuracy of the peak recorded on April 15 suggests the use of a calibrated portable heating device. He declined to speculate on what specific type of equipment.
previous cases
This is not the first episode involving suspicions of insider trading in prediction markets. The previous Thursday, a U.S. Army special forces soldier who participated in the capture of Venezuelan President Nicolás Maduro in January was accused of using classified information to bet on outcomes related to Venezuela. The soldier allegedly profited more than US$400.000 (R$2 million) in the operation. polymarket.
At the end of 2025, another user of the platform made a profit of approximately US$300.000 (R$1,5 million) betting on last-minute pardons granted by President Joe Biden before leaving office.
Declarations
“It was an isolated increase, at a single station, in the early evening,” Hallali said about the first recorded episode.
“The incident at Charles de Gaulle Airport is not an isolated curiosity,” said Hallali. “It’s what happens when financial incentives collide with a fragile data infrastructure.”
“Markets are expanding into all domains where an outcome can be observed, measured, and settled,” the expert noted. “As these markets multiply, so does the surface area for manipulation.”
O polymarket The company did not immediately respond to a request for comment on the case. Representatives from Charles de Gaulle Airport and airport police declined to comment beyond confirming that the case is under investigation.
