France Probes Polymarket Weather Data Glitch After $37,000 Traders Win

Polymarket traders won about $37,000 after unusual temperature spikes appeared in automated weather readings at Charles de Gaulle International Airport, triggering suspicion of manipulation tied to two Paris temperature contracts on April 6 and April 15.

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Bitget

The Straits Times reported that France’s forecasting office flagged suspected tampering with weather sensors at the country’s largest airport and referred the case to the police after detecting unusual readings alongside heavy betting on a popular prediction market.

CoinCentral

Cointelegraph and TradingView both described how the markets focused on the highest temperature in Paris on April 6 and 15, using the highest temperature recorded at the Charles de Gaulle Airport Station in degrees Celsius, according to Polymarket.

French outlet BFMTV reported on Monday that the temperature suddenly climbed to over 21 degrees Celsius on April 6 before dropping again immediately, and the market resolved with the winner taking over $16,000.

Bubblemaps said the spike did not show on nearby stations, and TradingView quoted Bubblemaps analysts saying, "That spike didn't show on nearby stations."

On April 15, Bubblemaps said the station held near 18 degrees Celsius most of the day, then briefly rose to 22 degrees Celsius before dropping back, and the move helped decide the Polymarket settlement.

The Straits Times added that automated temperature readings at Meteo France’s weather station spiked 4 deg C and 5 deg C unexpectedly in the evenings of April 6 and April 15, respectively, reaching the highest temperature recorded at the site on those days.

Multiple reports tied the Polymarket outcomes directly to automated temperature readings from Meteo France’s station at Charles de Gaulle International Airport, describing those readings as both commercially important and operationally critical.

The Straits Times said the readings are used to settle contracts for daily high temperatures on Polymarket, according to information on the website where traders place bets on real-world outcomes.

The Straits Times

It also stated that readings from the site are important for the safe operation of the airport, and that they are used for take-offs and landings, to determine which runways are used and helping air traffic controllers set routes and spacing between aircraft.

Cointelegraph and TradingView both said the contracts used the highest temperature recorded at the Charles de Gaulle Airport Station in degrees Celsius on April 6 and April 15.

The Straits Times reported that automated temperature readings spiked 4 deg C and 5 deg C unexpectedly in the evenings of April 6 and April 15, respectively, reaching the highest temperature recorded at the site on those days.

It further noted that betting on Paris temperatures switched to using data collected at Paris-Le Bourget Airport instead of Charles de Gaulle on April 19, according to Polymarket’s website.

The Straits Times also described how, on April 15, temperatures hit 18.8 deg C in the late afternoon and started to taper off before surging from 16.9 deg C to 21.9 deg C in 12 minutes, according to data from the weather station show.

The reports included direct statements from meteorological and weather-industry voices, alongside the French weather agency’s actions and the police response.

“Polymarket traders win $37K after Paris weather data glitch, raising suspicion Ruben Hallali, a meteorologist, told French media outlet BFMTV the temperature glitch was unlikely to be a natural event”

Cointelegraph

Cointelegraph and TradingView both quoted meteorologist Ruben Hallali telling BFMTV that the temperature glitch was unlikely to be a natural event, with Cointelegraph writing, "Such temperature variations seem very unlikely, especially on these two dates, and over such a short period."

TradingView added Hallali’s explanation that, "We can imagine that an individual with a good understanding of how the sensors work intervened, resulting in temperatures rising by two degrees at the right time, to validate a bet."

The Straits Times said Hallali, chief executive officer and co-founder of Paris-based weather intelligence firm HD Rain, was among those who reported the anomalous data to Meteo France, where he previously worked, and it quoted him saying, "That’s why I was able to spot very quickly the fact that there was a data manipulation."

On the government side, the Straits Times reported that a spokesman for Meteo France, Mr Laurent Becler, said technicians examined sensor data and inspected the weather station, and that the forecasting office subsequently filed a complaint for tampering with the operation of an automated data processing system to airport police.

Cointelegraph said Météo France has reportedly made a complaint with the police unit, the Roissy Air Transport Gendarmerie Brigade, for alleged tampering with the operation of its automated data processing systems.

The Straits Times said the airport police declined to answer questions about the complaint and referred questions to court officials, who declined to answer a request for more information, while Charles de Gaulle International Airport declined to comment.

While the core facts—two Paris temperature spikes tied to Charles de Gaulle readings and Polymarket payouts—were consistent across outlets, the framing and emphasis varied between investigative detail, market-integrity focus, and operational risk.

The Straits Times foregrounded the French response and airport implications, stating that France’s forecasting office referred the case to police and that the data give pilots and air traffic controllers critically important readings on temperature, wind, visibility and other conditions, with Hallali warning, "If there is a mistake in this data, it can be dangerous."

CoinCentral

Cointelegraph and TradingView emphasized the betting outcomes and the suspicious timing, noting that two Polymarket accounts attracted suspicion after making $37,000 betting correctly on two unusual temperature readings and that the market resolved with the winner taking over $16,000.

Cointelegraph also highlighted Bubblemaps’ observation that "That spike didn't show on nearby stations," and it described a trader action: "Just before the spike, one trader started buying NO shares on "18°C," before exiting with over $21, 000."

In contrast, the Bitget article presented the same $37,000 figure while adding a platform-oriented disclaimer and describing the contracts as tied to the highest temperature recorded at the Charles de Gaulle Airport station on April 6 and April 15.

CoinCentral’s emphasis was on Polymarket’s data reliability and manipulation risks, saying the incident raised integrity concerns around Polymarket data sources and that the station data are used to settle contracts for daily high temperatures.

Across outlets, the common thread was that the spikes were short-lived and did not persist across nearby monitoring stations, but the Straits Times treated the stakes as aviation safety while Cointelegraph and TradingView treated them as market manipulation and insider trading concerns.

The incident’s consequences, as described by the sources, include both immediate changes to how Polymarket settles Paris temperature bets and broader scrutiny of prediction markets’ data integrity.

“Polymarket traders win $37K after Paris weather data glitch, raising suspicion Two Polymarket accounts have attracted suspicion after making $37,000 betting correctly on two unusual temperature readings of a weather station located in a major airport in France”

TradingView

The Straits Times reported that betting on Paris temperatures switched to using data collected at Paris-Le Bourget Airport instead of Charles de Gaulle on April 19, according to Polymarket’s website, after the earlier anomalies were flagged.

The Straits Times

It also said that the case was referred to police and that Meteo France filed a complaint for tampering with the operation of an automated data processing system to airport police, with the airport police declining to answer questions and referring questions to court officials.

Cointelegraph and TradingView both said Météo France has reportedly made a complaint with the police unit the Roissy Air Transport Gendarmerie Brigade for alleged tampering with automated data processing systems.

Cointelegraph also described prediction markets facing growing scrutiny over insider trading and possible violations of gambling laws, linking the Paris episode to broader concerns.

The Straits Times provided a quantitative context for betting volume, saying the contracts attracted roughly US$1.4 million (S$1/8 million) in combined bets, according to Polymarket data, and that total betting for each was more than double the typical volume for other daily Paris temperature contracts in April.

Hallali told the Straits Times that the consequences of tampering with sensors at an airport could be severe and said, "If there is a mistake in this data, it can be dangerous."