A Frenchman “manipulated” Paris weather sensors, earning $34,000 in Polymarket profits

According to disclosures made on April 23 on X by the crypto community account @aaronjmars, as well as subsequent reporting by Le Monde and BFMTV, a man interfered with the Paris Charles de Gaulle (CDG) airport’s automatic weather sensors with a portable heating device on April 6 and April 15, respectively, generating cumulative profits of approximately $34k in the weather betting markets of Polymarket.

Records of Two Sensor Anomaly Incidents

(Source: Polymarket)

According to a Météo-France statement and reporting by Le Figaro:

April 6 incident: Around 6:30 p.m., the CDG weather station’s sensor recorded a sudden jump in temperature by about 4 degrees Celsius within 12 minutes, briefly reaching 22.5 degrees Celsius, before dropping back to normal levels. According to Le Monde and BFMTV reports, at least one bettor received roughly $14k in winnings for betting that Paris temperatures would reach 21 degrees Celsius; the account was created within the days before the incident.

April 15 incident: Around 9:30 p.m., under clear-sky conditions, the sensor temperature readings climbed to 22 degrees Celsius and then dropped again a few minutes later. According to the aforementioned media reports, another bettor received approximately $20k in winnings for betting that the temperature would reach 22 degrees Celsius.

Météo-France confirmed that during both incidents, nearby weather stations recorded no similar temperature changes, and there were no corresponding changes in wind direction or relative humidity. Meteorologist and founder of E-Meteo Service, Paul Marquis, told Le Figaro: “There was no change in wind direction and relative humidity, and other weather stations did not record any anomalies.” Marquis said that the most plausible explanation is that someone placed a heating device near the sensor probe.

Involved Agencies: Météo-France Complaint and CDG Sensor Location

According to Météo-France’s public statement, after reviewing physical observation data from the automated weather station at Charles de Gaulle Airport and the sensor logs, the agency filed an official complaint with the Roissy air transport gendarmerie, accusing the offense of “tampering with the operation of an automated data processing system.” After Météo-France confirmed that the complaint had been filed, it refused to provide further public comments on the matter.

The CDG weather station is located near the runways and can be accessed from public roads. Polymarket uses data from this station as the market settlement source for calculating Paris’s daily maximum temperature. As of April 23, no arrest records or suspect identities have been published.

Change of Polymarket Data Source and Media Tracking

(Source: Polymarket)

According to an announcement updating the Polymarket platform rules, around April 19 the platform changed the settlement data source for the Paris temperature market from the CDG weather station to sensors at Paris Le Bourget Airport.

The incident initially drew attention on the French weather forum Infoclimat.fr, where users flagged the related data anomaly within hours after the April 6 incident occurred. The discussion then spread to X, with the relevant posts widely circulated, and the incident entered France’s mainstream media, including reports by Le Monde, Le Figaro, and BFMTV.

Frequently Asked Questions

Which agency did the French meteorological authority file a complaint with regarding the sensor tampering case?

According to Météo-France’s public statement, the agency has filed an official complaint with the Roissy air transport gendarmerie (Gendarmerie des transports aériens de Roissy), accusing the offense of “tampering with the operation of an automated data processing system.” The timing of the complaint has been confirmed as after Météo-France completed its review of the sensor data.

When did the two Polymarket weather betting anomaly incidents occur, and what were the amounts involved?

According to reports by Le Monde and BFMTV, the first incident occurred on April 6, and the relevant bettors received approximately $14k in winnings; the second occurred on April 15, and the relevant bettors received approximately $20k in winnings. In total, the two incidents paid out approximately $34k.

What measures did Polymarket take after the incident was exposed?

According to a Polymarket platform announcement, around April 19 the platform changed the settlement data source for the Paris temperature weather market from the Charles de Gaulle Airport (CDG) weather station to sensors at Paris Le Bourget Airport in order to cut off reliance on the affected, interfered-with site.