Highest temperature in Paris on June 28?

Platform comparison

Market context

On 28 June 2026, Paris-Le Bourget will record its peak temperature for the day, a real-world event that determines the outcome of this prediction market. The crowd-implied probability for a YES outcome sits at 0%, reflecting a near-universal consensus that the temperature will not exceed the highest threshold in the market’s range. Historical data frames this stark probability: late-June heatwaves in Paris have occasionally shattered records, with 28 June 2019 yielding 44.3°C at the station, and France’s all-time peak reaching 45.9°C in southern regions [6][8]. Yet, recent trends show cooling, and current model agreement clusters tightly around 30–32°C, suggesting the underdog (higher temperature) is vastly out of value [1].

Traders should monitor the Met Office’s forecast updates, which indicate conditions improving by Friday following an early heatwave that gripped Europe [3]. The key catalyst is the timing of the next high-pressure system over western France; if it arrives late, peak temperatures may remain suppressed. Recent AP News coverage confirms the heatwave’s intensity but notes expected relief, reinforcing the contrarian angle that betting on the favourite (lower temperature) offers minimal value given the 0% implied probability [3]. The value spot likely lies in a small, contrarian bet on the underdog, as historical extremes suggest the market may be underestimating residual uncertainty in peak temperature forecasts [1][2].

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 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.