French Authorities Investigate Weather Sensor Tampering at Paris Airport Linked to $34,000 in Polymarket Bets
French officials are investigating suspected tampering with a weather sensor at Charles de Gaulle Airport in Paris after two abnormal temperature spikes in April 2026 coincided with large winnings on Polymarket, the world’s largest prediction market. The incidents occurred on April 6 and April 15, when portable heating devices were used to artificially raise temperature readings at the airport’s weather station, triggering payouts totaling approximately $34,000.
According to reports, the weather sensor—located on the edge of the runway near a public road—was heated using a hairdryer or similar portable device. On April 6, between 6:30 PM and 6:42 PM, the temperature reading rose by 4°C in just 12 minutes, reaching 22.5°C before dropping back within five minutes. A similar spike occurred on April 15 around 9:30 p.m., when the temperature briefly surged to 22°C after holding steady near 18°C for most of the day. Neither anomaly was detected at nearby weather stations, and the actual temperature in Paris did not show such fluctuations on those dates.
The abnormal readings aligned with specific outcomes on Polymarket’s “daily high temperature in Paris” markets. On April 6, the spike corresponded to the “21°C” option, which had previously attracted little interest. On April 15, traders who had bet against the “18°C” outcome—buying “NO” shares—exited with significant profits after the brief surge. Blockchain analysis tools identified one account that opened just two days before the first incident and collected approximately $14,000 from the April 6 event. Total winnings from both incidents were reported as $34,000 by some sources, while others cited figures closer to $37,000, reflecting differing calculations of profits across multiple bets.
Météo-France, the national meteorological service, confirmed it filed a formal complaint with the Air Transport Gendarmerie Brigade of Roissy after detecting physical evidence of tampering and analyzing sensor data. A spokesperson stated: “In view of physical findings on one of our instruments and the analysis of sensor data, Météo-France was indeed led to file a complaint for alteration of the operation of an automated data processing system.” The agency declined further comment while the investigation remains ongoing.
Experts have noted the unlikelihood of such rapid, localized temperature changes under natural conditions. Ruben Hallali, a meteorologist speaking to BFMTV, said: “Such temperature variations seem very unlikely, especially on these two dates, and over such a short period.” The Infoclimat Association also suggested that recent operate on the station’s shelter may have contributed to aberrant readings, though authorities maintain the spikes were externally induced.
In response to the incident, Polymarket has not publicly commented, but analysts warn the event highlights vulnerabilities in prediction markets that rely on real-world data oracles. The case may prompt increased scrutiny of data integrity and security measures around environmental sensors used as inputs for financial markets.
As of April 23, 2026, the investigation continues, with French authorities examining surveillance footage, sensor logs, and transaction trails to identify those responsible. No arrests have been made, and the anonymous account that received the funds remains under scrutiny by blockchain analysts and financial investigators.