The unusual temperature fluctuations recorded at a key Paris weather station have sparked an official investigation after a trader on Polymarket reportedly earned around $37,000 from highly improbable bets.
The wagers were linked to daily temperature prediction contracts based on data from a Météo-France monitoring station at Charles de Gaulle (CDG) Airport.
Authorities flagged irregularities on April 6 and April 15, when temperatures briefly spiked beyond expected levels before quickly normalising.
On April 6, readings momentarily crossed 21°C, while on April 15, the temperature jumped to nearly 22°C after staying around 18°C for most of the day.
These spikes depicted the highest recorded temperatures for the days mentioned, allowing some bets to pay out, according to Bloomberg.
The 'Missing' Evidence & Insider Suspicion
Data analysis firms Bubblemaps and NS3. AI identified a specific trader who seemingly anticipated these "impossible" spikes.
Just minutes before the artificial surge on April 15, the trader aggressively bought "NO" shares on the 18°C threshold contract. This perfectly timed move allowed the trader to profit when the rogue reading pushed the official temperature above the limit, settling the market in their favor.
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Official Legal Action
Météo-France has taken the rare step of filing a formal police complaint, citing suspected sensor tampering or a cyber-intrusion into their automated reporting systems.
The agency noted that no other nearby stations recorded similar spikes, suggesting a localized breach specifically at the CDG monitoring unit.
Impact on Prediction Markets
The incident has drawn attention to the vulnerability of data-dependent betting platforms (or "Oracles").
Polymarket relies on official government feeds to settle contracts; this breach demonstrates that if the "ground truth" source is compromised, decentralised platforms have no choice but to pay out on fraudulent data.
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