Two Polymarket accounts are under scrutiny after they won about $37,000 from weather prediction markets tied to Paris temperatures.
Summary
- Two traders made $37,000 after short-lived temperature spikes settled Paris weather markets on Polymarket unexpectedly.
- Bubblemaps flagged one account that bought before the April 15 spike and later exited profitably.
- Météo France filed a complaint after reports linked unusual airport temperature readings to possible tampering.
The contracts used the highest temperature recorded at the Charles de Gaulle Airport station on April 6 and April 15.
On both dates, the market outcome appeared to turn on short-lived jumps in temperature readings. French outlet BFMTV reported that the station moved above 21 degrees Celsius on April 6 before quickly falling again. That result helped settle one market, with the winning side taking more than $16,000.
Second spike drew more attention from blockchain analysts
A similar pattern appeared in the April 15 market. Bubblemaps said the station held near 18 degrees Celsius for most of the day, then briefly rose to 22 degrees Celsius before dropping back. The move helped decide the market and added to concerns around the data source.
Bubblemaps said one trader bought NO shares on “18°C” just before the spike and later exited with more than $21,000 in profit. The analytics firm also noted that the jump did not appear on nearby stations. That detail added more attention to the timing of the trade and the recorded reading.
Meteorologist questions whether the fluctuation was natural
Ruben Hallali, a meteorologist, told BFMTV that the sudden change did not look like a normal weather event. He said the movement in the readings over such a short time was hard to explain through natural conditions alone.
“Such temperature variations seem very unlikely, especially on these two dates, and over such a short period,” Hallali added. “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.”
Furthermore, Météo France, the country’s official weather agency, has reportedly filed a complaint with the Roissy Air Transport Gendarmerie Brigade. The complaint concerns alleged tampering with its automated data processing systems linked to the weather station readings.
