A polymarket trader has made nearly $37,000 in profits after taking advantage of strange weather data in Paris. This win has drawn attention from analysts and revived wider concerns about transparency and potential manipulation in prediction markets.
The controversy is about two separate markets predicting the highest temperature recorded in Paris on April 6 and April 15. Both markets relied on data from a weather station located at Charles de Gaulle Airport.
The controversy surrounding Polymarket Trader
On each occasion, the readings showed sudden and short-lived spikes that ultimately determined the winning outcomes and moves that proved highly profitable for at least one polymarket trader.
According to reports, temperatures on April 6 unexpectedly surged above 21°C before quickly falling back. That brief spike was enough to settle the market, allowing the winning side to collect more than $16,000.
A similar pattern occurred on April 15, when temperatures hovered around 18°C for most of the day, only to jump to 22°C momentarily. The second event brought another $21,000 in gains for a well-positioned polymarket trader.
Bubblemaps, a blockchain data analytics company, pointed out some irregularities in trading ahead of the surge on April 15. It was observed that a polymarket trader had initiated purchases of “NO” stocks linked to 18° C prior to the occurrence, making profits from such deals.
The peculiar thing is that the nearby weather observation posts did not observe any temperature changes. Weather expert Ruben Hallali shared his opinion as well, saying that such sudden and localized changes in temperature were improbable under regular circumstances.
He indicated that someone with technical knowledge of how weather sensors operate could, in theory, interfere with readings to influence outcomes, an unsettling possibility for any polymarket trader relying on fair data.
The situation has now drawn official attention. The French national weather service, Météo France, is said to have made a complaint against aviation police because it was worried that its automated system had been hacked.
With the continued proliferation of prediction markets, it becomes all too clear just how significant data integrity can be in such an environment. For every polymarket investor seeking genuine profit, data integrity is essential for the success of the industry as a whole.