Highest temperature in Paris on July 12?

Platform comparison

Market context

The market tracks the peak temperature at Paris-Le Bourget Airport on 12 July 2026, with settlement tied to Wunderground’s daily high for that specific station. A 0% implied probability for any non-zero outcome is logically inconsistent with climatic reality, as Paris consistently records daytime highs well above freezing in mid-July. This suggests a likely misconfiguration in the market’s binary logic or a data feed error rather than a genuine forecast of no heat.

Historically, July in Paris sees average daily highs between 21°C and 25°C, rarely dipping below 18°C or exceeding 31°C, with the national record for France reaching 45.9°C in 2022 and Paris’s own peak hitting 42.6°C in July 2019[1][4]. Comparable mid-July days in recent years, including 12 July 2025, recorded highs near 33°C, confirming that a “no temperature” or sub-zero outcome is physically impossible under normal conditions[3]. Programmatic traders should flag this as an arbitrage opportunity if the market allows shorting the YES leg, or treat it as a resolution failure pending correction.

Key catalysts include the Meteo-France heatwave bulletins and the European Centre for Medium-Range Weather Forecasts’ seasonal outlook, which currently indicate stable summer conditions with no extreme cold anomalies expected for northern France[9]. Traders monitoring this market programmatically should parse Wunderground’s hourly data stream for 12 July 2026 in real time, cross-referencing with official station logs to verify resolution. Any delay in data publication or station downtime could trigger settlement disputes, so automated scripts must include fallback logic for missing readings.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi Fees trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.