Highest temperature in Paris on August 6?

Platform comparison

Market context

Paris is expected to peak in the mid-20s Celsius, with short-range guidance around 25–26°C for 6 August and a recent forecast calling for a largely sunny day and a maximum near 26°C. That sits close to Paris’s August norm rather than in the kind of extreme heat regime that would push the upper temperature range materially higher. [13][10][2]

For a market priced with a 0% YES crowd-implied probability, the practical read is that the contract is still sensitive to any late model wobble by a degree or two, because the settlement source is the day’s *highest* reading at Paris-Le Bourget Airport, not a citywide average. Comparable summer forecasts in Paris usually cluster around the mid-20s, so programmatic traders would typically map the likely outcome by scraping the station forecast, then watching whether updated hourly observations or a small afternoon spike move the realised maximum into the adjacent band. [13][10][1]

The main catalysts are the morning and early-afternoon weather updates, since cloud cover, showers or thunderstorms can trim the top end, while a sunnier afternoon can lift the max by a degree. Short-range forecasts and any official Météo-France commentary matter more than broader seasonal context, especially after France’s recent early-summer heat episodes showed how quickly conditions can swing from normal to exceptional. For automated execution, the useful checks are forecast refresh times, the station’s observation feed, and the market’s own settlement rule that locks in after the first datapoint for the following date appears. [13][14][11][4]

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.