$34,000 From a Hairdryer? Police Are Investigating a Weather Sensor Hack at a Major Airport Linked to Crypto Bets

French authorities have opened a criminal investigation after suspicious temperature spikes at a Paris airport sensor coincided with two high-value bets on Polymarket.

A total of $34,000 was won on weather bets after temperature readings at Charles de Gaulle airport surged suspiciously on April 6 and April 15, amid claims that a sensor had been tampered with. Both spikes coincided with the placement of high-value wagers on Polymarket, the world’s largest prediction market.

“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 with the Air Transport Gendarmerie Brigade of Roissy,” a spokesperson said.

Forecasting weather patterns has grown into a profitable activity on the platform, which relies on Météo-France data recorded at Charles de Gaulle to resolve wagers on the city’s peak daily temperature.

On both April 6 and April 15, the airport’s weather sensor recorded unexpected late-day temperature spikes that far exceeded forecasts—rising to 21C (70F) at 7pm and 22C (72F) at 9:30pm respectively—despite hovering around 18C (64F) for most of both days.

The odds of temperatures exceeding 18C (64F) on either day had been estimated at just one percent, meaning those who wagered on such an unlikely outcome stood to collect massive payouts. One trader alone walked away with $21,000 on April 15th, with total winning bets on the day reaching $34,000.

The unusual readings quickly caught the attention of weather enthusiasts, who were among the first to raise concerns. “We thought it was an issue with the sensors ,” Sébastien Brana, who runs an online weather forum whose members track Météo-France data in near real time, told The Financial Times. “You can have sudden temperature changes at sundown when there is a storm as well. But the weather situation didn’t explain what was happening. It became clear there was something else going on when it happened again on April 15.”