French authorities have launched an investigation into suspected manipulation of national weather data following unusual temperature readings that coincided with high-value betting activity on a blockchain-based prediction platform. State weather agency Météo-France confirmed it has opened an inquiry to assess whether its meteorological infrastructure was compromised after anomalies were detected in temperature data near Paris.
The investigation comes after a series of unexpected temperature spikes triggered significant payouts on Polymarket, where users place bets on real-world outcomes. Officials are examining whether individuals may have interfered with the system either physically or digitally to influence recorded data.
Attention has focused on a weather sensor located near Charles de Gaulle Airport, which reportedly recorded a sudden increase of around 4°C within 12 minutes on April 6. The reading crossed a key threshold used to settle betting contracts, despite other data sources indicating lower temperatures.
A user on the platform had placed aggressive bets predicting higher temperatures on that day, contrary to prevailing forecasts, and is reported to have earned close to €30,000. A second similar anomaly on April 19 further raised suspicions of possible tampering.
Unverified online claims have suggested that the spike may have been artificially induced using a heat source, such as a hair dryer, although authorities have not confirmed these reports. Investigators are focusing on whether the integrity of the automated data system was intentionally altered.
Météo-France stated that it has filed a formal complaint with the Roissy air transport gendarmerie brigade, citing potential interference with an automated data processing system. The probe aims to determine whether external manipulation affected the accuracy of official weather readings.
Following the incident, Polymarket suspended reliance on the affected sensor and shifted its data source to a station at Paris–Le Bourget Airport. However, previously settled contracts were not cancelled, leaving the disputed payouts intact.
The case has intensified scrutiny of “oracles,” the data feeds used in decentralised finance platforms to determine outcomes of prediction-based contracts. These systems rely heavily on external data sources, and any compromise at the source level can directly impact financial outcomes.
Experts say the incident highlights a growing risk in digital markets, where manipulation of real-world inputs can be used to exploit automated financial systems. The decentralised nature of such platforms also makes enforcement and recovery of funds more complex once transactions are completed.
Authorities continue to investigate the matter, as the case underscores emerging challenges at the intersection of technology, finance and data integrity.
