Hair dryer trick behind €25,000 win? France probes potential weather data scam linked to Polymarket

By Quirino Mealha Published on 23/04/2026 - 16:10 GMT+2 Share Comments Share Facebook Twitter Flipboard Send Reddit Linkedin Messenger Telegram VK Bluesky Threads Whatsapp

Officials in France have launched an investigation into the potential compromise of national weather sensors after a series of anomalous temperature readings coincided with betting activity on Polymarket.

Météo-France has initiated an inquiry to determine whether the meteorological infrastructure managed by them was targeted by individuals seeking to influence prediction markets.

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This development follows reports of highly unusual temperature spikes that triggered significant financial payouts on the blockchain-based site Polymarket, where users place wagers on real-world events.

Investigators are examining if the integrity of the national weather network was breached through physical or digital interference, as the precision of the winning bets suggests the actors involved may have had direct control over the reported data.

Online rumors, which remain unverified for the time being, claim the temperature reading was manipulated by someone using a hair dryer to generate a higher temperature.

Polymarket reportedly settles Paris temperature bets on a single Météo-France sensor sitting near the Charles de Gaulle airport perimeter.

On 6 April, the reading from the sensor abruptly rose 4°C in twelve minutes, crossing the 22°C threshold despite data from other sources showing different figures.

A user on Polymarket aggressively bet on readings above 21°C on that specific day, even though the consensus was lower at 18°C, and profited almost €30,000.

A second similar anomaly occurred on 19 April leading to suspicions that the sensor was tampered with.

Météo-France announced that it has filed a complaint with the Roissy air transport gendarmerie brigade "for [the] alteration of the operation of an automated data processing system," after an analysis of sensor data.

Polymarket suspended its reliance on the compromised weather data source for Paris, shifting its resolution metric from the sensor in Charles de Gaulle airport to the one in Paris-Le Bourget airport.

However, it did not cancel the contracts or refund the bets, leaving the resolved contracts final, even though on previous occasions it has suspended the resolution of certain bets until further clarification on the rules and circumstances.

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Decentralised 'oracles' and prediction markets

This incident has reignited the debate over the reliability of the "oracles" that feed data to prediction markets in order to settle bets.

In decentralised finance, an oracle is the mechanism that feeds external, real-world information into a smart contract to determine a financial outcome.

Polymarket relies on these feeds to settle its contracts, often pulling data directly from official government websites. If the primary source of that data is corrupted, the betting market lacks any internal mechanism to verify the truth.

Additionally, the decentralised nature of these platforms makes it difficult to freeze assets even if an investigation identifies the individuals behind suspicious trades.

This is the latest case that highlights a new frontier of white-collar crime, where the manipulation of the physical world is used to exploit the vulnerabilities of automated prediction markets in order to win bets on real-world events.

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