Météo-France Files Criminal Complaint After Anomalous Paris Airport Readings Settled Polymarket Bets

Météo-France has filed a criminal complaint after two brief, anomalous temperature spikes at Paris Charles de Gaulle Airport were used to settle Polymarket weather bets, paying traders roughly the mid-$30,000s and turning a niche market dispute into a police matter.

The French national weather service told BFMTV and Le HuffPost that it filed the complaint with the Roissy air-transport gendarmerie brigade after detecting suspicious anomalies at its automated weather station at the airport. Météo-France said the reported offense was “altération du fonctionnement d’un système de traitement automatisé de données,” or interference with the operation of an automated data-processing system.

The readings in question were recorded on April 6 and April 15 at the Charles de Gaulle station used to resolve Polymarket’s Paris temperature markets. Reporting said the spikes were short evening jumps, reaching about 22.5 degrees Celsius on April 6 and about 22 degrees Celsius on April 15.

Those readings stood out because nearby weather stations did not show similar moves, according to analysts cited in reports, suggesting the anomalies were isolated to the airport sensor rather than reflecting broader weather conditions in the Paris area. That discrepancy is now at the center of the complaint and the reported investigation.

The data was consequential because Polymarket, a blockchain-based prediction market, settles contracts according to designated outside sources. In these markets, the source was Weather Underground data tied to the Charles de Gaulle station. Once the spikes appeared in that feed, the contracts were resolved and two traders were paid.

Reported totals vary by outlet, with some putting the combined payouts at about $34,000 and others at about $37,000. One commonly cited breakdown was roughly $14,000 after the April 6 spike and about $20,000 after the April 15 spike.

Some of the trading around the markets has also drawn scrutiny. Cointelegraph, citing blockchain analytics firm Bubblemaps, reported unusual trading just before one of the spikes. Bubblemaps analysts told Cointelegraph, “That spike didn’t show on nearby stations.” The same report said, “Just before the spike, one trader started buying NO shares on 18°C,” before exiting with more than $21,000.

Reporting also said at least one winning Polymarket account had been opened recently, though outlets differed on the timing. Le HuffPost said one account was created 48 hours earlier, while Cointelegraph described it as less than 30 days old.

Polymarket’s own market pages showed the Paris contracts were being resolved using Weather Underground data from Charles de Gaulle. After the anomalies, later Paris weather markets listed Paris-Le Bourget as the resolution station instead, indicating the platform changed the data source used for those contracts. There was no public reporting that Polymarket had reversed the earlier resolutions or clawed back the payouts.

The incident offers a clear example of the “oracle” problem in crypto and prediction markets: Even when contracts settle automatically, the result still depends on the integrity of the outside data feed. Here, a single physical sensor appears to have influenced market outcomes and triggered a criminal complaint.

French authorities were reported to have been notified, and the complaint and investigation are open. No arrests or suspect identifications had been publicly reported.