Hair dryer suspected after Paris airport sensor paid $34,000

Météo France confirmed it filed a criminal complaint after two unexplained temperature jumps at its automated station at Paris Charles de Gaulle Airport matched payouts on the prediction market Polymarket.

The first anomaly occurred on April 6 at about 6:30 p.m., when the sensor recorded a roughly 4°C rise within 12 minutes, briefly reaching 22.5°C before returning to normal. The second happened on April 15 at about 9:30 p.m., when the reading rose to about 22°C under calm, cloudy conditions and fell back within minutes. Neighboring stations showed no similar changes, and wind direction and relative humidity at the times of the anomalies did not register corresponding shifts.

Météo France filed the complaint with the Roissy air transport gendarmerie brigade for “alteration of the operation of an automated data processing system.” The CDG automated station sits near the runway perimeter and is reachable from a nearby public road. Météo France declined to provide further comment beyond confirming the complaint.

Paul Marquis, founder of E-Meteo Service, called natural causes unlikely given the lack of changes in wind or humidity and the absence of similar readings at surrounding stations. He described a heating device placed close to the sensor probe as the most plausible explanation for the pattern.

Polymarket, which settles some Paris temperature contracts using the CDG station, paid roughly $14,000 after the April 6 spike and about $20,000 after the April 15 spike, for combined payouts near $34,000. At least one winning account was created days before the first anomaly. Users on the platform flagged the outcomes in real time with comments alleging manipulation and insider trading. Around April 19, Polymarket changed the resolution source for Paris temperature markets from the CDG sensor to the Paris–Le Bourget station.

No arrests or identifications of suspects have been announced and the investigation remains open. The incidents prompted discussion among meteorology observers and online communities about the use of single-sensor measurements to settle financial bets.