French Police Investigate Possible Manipulation of Weather Data for Betting on Polymarket

^{Wind direction at the airfield / © Shutterstock}

French authorities are investigating possible manipulation of weather data used for betting on the Polymarket platform, Bloomberg reported.

The case involves a weather station operated by Météo-France at Charles de Gaulle Airport. On April 6 and 15, sensors recorded sudden temperature spikes of 4–5 degrees Celsius. In one instance, the reading rose from 16.9°C to 21.9°C in just 12 minutes, while humidity dropped sharply at the same time.

The data are used not only for meteorological monitoring but also for airport operations, including take-offs and landings, as well as flight routing and performance calculations.

Meanwhile, Polymarket saw a surge in bets on the maximum temperature in Paris on those dates.

Total betting volume reached about $1.4 million — more than double the typical level.

In one case, a user earned more than $21,000 by betting that temperatures would exceed forecasts.

The anomalies were first flagged by traders and meteorologists, prompting a review of the equipment.

Following the review, Météo-France filed a complaint with the police over suspected interference with its automated data processing system.

After the incident, Polymarket changed the data source used to settle bets. The manipulation has not been officially confirmed and the investigation is ongoing.

Gambling Park notes that a study found 84% of Polymarket users trade at a loss.