How Polymarket resolves weather markets — and what happened at Roissy in April 2026
A French airport temperature sensor, a series of unusual readings, a silent oracle swap, and a criminal complaint filed with the French aviation-transport gendarmerie. Here is what is verified, what is alleged, and what it means for anyone holding a Polymarket weather position.
Our policy on this page
We quote Polymarket docs and the Météo France complaint verbatim where possible. We do not paraphrase beyond what public reporting or primary sources say.
- We do not publish suspected bettor wallet addresses or any user name — no matter how widely a French-press outlet cites one.
- We do not characterize the sensor anomaly as 'fraud'. That determination is for French investigators and a court.
- We do not recommend third-party 'oracle bypass', 'resolution recovery', or 'dispute-assistance' tools.
- We cite dollar amounts from French-press reporting only with explicit 'per [outlet]' attribution and an 'unconfirmed by Polymarket / Météo France' caveat.
- We do not link to Infoclimat forum quotes as primary source; only as quoted through Le Figaro or BFMTV.
- We quote Polymarket docs and the Météo France complaint verbatim where possible; we never paraphrase into policy claims they did not make.
- We add a same-session re-fetch timestamp on every primary source — Polymarket docs have silently revised dates before (Apr 17→Apr 19 V2 cutover revision is the documented precedent).
- We publish a 'verify your market's oracle' utility checklist rather than a 'winners list' — the page is user-protective, not voyeuristic.
The 30-second answer
What is an oracle in prediction markets?
An oracle is the external data source a prediction market uses to decide the outcome. Polymarket's resolution layer uses UMA's Optimistic Oracle (the current production version is sometimes called OOv2 or MOOv2 depending on contract). Every Polymarket contract additionally names a specific, human-readable data source in its rules — for weather markets, that usually means a specific airport station ID (for example Roissy-CDG / LFPG, or Le Bourget / LFPB). UMA is how disagreements are adjudicated; the named station is what the adjudication is checked against.
How Polymarket names a resolution source
Every Polymarket contract names a resolution source in its market rules. For weather, that is typically an airport station ID plus a data provider.
| Category | Primary source | Named in contract? |
|---|---|---|
| Weather (US & EU) | Airport weather station (ASOS/METAR feed) | Yes — by IATA code or station ID in the contract's rules |
| Crypto price | Named exchange (e.g. Binance) or Chainlink feed | Yes — named in the resolution source field |
| Sports | League-specified scorekeeper or official box score | Yes |
| Geopolitics / elections | Newswire (e.g. Reuters, AP) or official election-authority source | Yes |
Polymarket Paris weather oracle — before and after the swap
Paris high/low temperature (pre-2026-04-19)
Station: Roissy-CDG (LFPG)
Data provider: Météo France airport observation series
Swapped out on or around 2026-04-19 per 4+ independent French outlets.
Canonical confirmation: Live Polymarket Paris-weather market 'Resolution source' field.
Paris high/low temperature (post-2026-04-19)
Station: Le Bourget (LFPB)
Data provider: Météo France airport observation series
Current resolution station for Polymarket Paris temperature markets following the April 19 swap.
Canonical confirmation: Live Polymarket Paris-weather market 'Resolution source' field.
The Roissy timeline
All dates and dollar ranges are drawn from French-press reporting and are being verified verbatim against primary sources. Dollar figures are cited with explicit outlet attribution and an “unconfirmed by Polymarket or Météo France” caveat.
- 2026-04-0618:30–18:42 CETVerification pending
Roissy-CDG temperature sensor reads jump sharply (reported as roughly +4°C in ~12 minutes) to a figure above 22°C, then drop several minutes later.
What happened next: A Polymarket Paris-temperature market resolves YES on the elevated reading.
Approximately $14,000 winning payout reported by Le Figaro (per Le Figaro Apr 21, unconfirmed by Polymarket or Météo France).
Source: Le Figaro Apr 21 2026 chain-of-events reconstruction outlet site
- 2026-04-15Verification pending
A second unusual excursion on the same sensor.
What happened next: A Polymarket 'Paris high = 22°C' market that had traded at a very low pre-event price (reported near 0.1% per Le Figaro) resolves YES.
Approximately $20,000 winning payout reported by Le Figaro (per Le Figaro Apr 21, unconfirmed by Polymarket or Météo France).
Source: Le Figaro Apr 21 2026 chain-of-events reconstruction outlet site
- 2026-04-19Verification pending
Polymarket swaps the Paris weather oracle from Roissy-CDG to Le Bourget.
What happened next: Future Paris weather contracts now resolve on Le Bourget (LFPB) station data. No public governance-layer announcement was located at the time of swap; the change was identified by French press cross-referencing live market rules.
Source: Confirmed across 4+ independent French outlets (Le Figaro, BFMTV, TF1, Journal du Coin, Cryptoast, Actu Roubaix) outlet site
- 2026-04-21Evening CETVerification pending
Météo France files a criminal complaint with the Brigade de Gendarmerie du Transport Aérien.
What happened next: French press reports the complaint cites the framing 'altération du fonctionnement d'un système de traitement automatisé de données' (an offense under French penal law). An investigation is opened.
Source: Le Figaro Apr 21 18:44 CET; BFMTV (Raphael Grably) Apr 21; TF1 20H Apr 21; Actu Roubaix Apr 21 20:28 CET outlet site
The silent oracle swap — why it matters
- An 'oracle swap' means the data source a future contract resolves on has changed — from one named station to another.
- It does not retroactively change how already-settled markets resolved.
- Polymarket has not, as of this page's publish timestamp, published a governance-layer statement identified in our primary-source sweep explaining the swap. If one is posted, this page is updated same-day.
- If you hold an open Polymarket Paris temperature position, open the market page now and confirm which station appears in its 'Resolution source' field.
What we are NOT saying
- We are not naming any suspected bettor or wallet address. Public reporting has not linked the sensor anomalies to specific Polymarket accounts with adjudicated proof.
- We are not characterizing this as 'fraud'. Whether the anomaly was natural, equipment failure, or deliberate interference is for French investigators and a court to determine.
- We are not recommending any third-party 'oracle bypass', 'resolution dispute', or 'refund recovery' tool. No such service is authorized by Polymarket.
- Dollar amounts cited on this page are from French-press reporting and have not been confirmed by Polymarket or Météo France.
Verify the oracle on YOUR market — a 6-step check
- Step 1. Open your specific Polymarket market page on polymarket.com.
- Step 2. Scroll to the 'Resolution source' or 'Market rules' section.
- Step 3. Confirm the named station ID (Roissy-CDG / LFPG vs. Le Bourget / LFPB vs. another station).
- Step 4. Cross-check the data provider (usually Météo France for European airports; NOAA/ASOS for US airports).
- Step 5. After the Polymarket V2 cutover, re-verify the Resolution source field on the new UI — do not assume the pre-cutover value carried through.
- Step 6. If the resolution source field is missing or ambiguous, check docs.polymarket.com and the market's UMA dispute history before you trade or accept settlement.
What this means for the V2 cutover
Post-cutover, re-verify the 'Resolution source' field on your specific Paris weather market in the new UI. Station names (LFPG vs LFPB) should carry through, but every contract-rules field should be confirmed, not assumed.
Frequently asked questions
Primary sources
- Le Figaro — Apr 21 2026 18:44 CET frOriginal French-language publication of the chain-of-events reconstruction.
- BFMTV — Raphael Grably Apr 21 2026 frBroadcast + web reporting on the Météo France complaint and oracle swap.
- TF1 — 20H news segment Apr 21 2026 frNational broadcast confirmation.
- Actu Roubaix — Apr 21 2026 20:28 CET frRegional reprint picking up the Le Figaro chain.
- docs.polymarket.com/changelog enPrimary source for any Polymarket statement on the oracle swap and for V2-migration status.
- Live Polymarket Paris-weather market — 'Resolution source' field enCanonical per-contract confirmation of which station ID resolves the market.
- Météo France frOfficial data provider for French airport weather observations.
29 domains are on this page's blocklist for unreliability or affiliate conflict — none appear in citations above. Foreign-language outlets are quoted only through the corresponding French-press reconstruction.
Re-verify within 24 hours while the French press cycle rolls. Mandatory re-verify same-day on any oracle-swap confirmation, any new criminal-complaint filing, any Polymarket public statement, or any V2-migration copy change.
A note on how we covered this
PredictionMarkets.US does not name suspected bettors, does not characterize the sensor anomalies as fraud, does not link third-party “oracle bypass” or “resolution recovery” tools, and does not take a position on the underlying French investigation. Every dollar amount on this page is cited with outlet attribution and an “unconfirmed by Polymarket or Météo France” caveat. We update same-day if Polymarket or Météo France issues a public statement that shifts the facts.