Highest temperature in London on July 23?

Platform comparison

Market context

The real-world event is the **highest temperature recorded at London City Airport Station** during the settlement window on 23 July 2026, with the market resolving to the temperature band that contains that observed peak. In prediction-market terms, a **YES** share pays out if the final recorded maximum lands in the specified range, while a **NO** share pays if it does not; here, the crowd is assigning **0%** to YES, which implies traders currently see that band as essentially out of the money under the market’s range structure.[1]

For context, London’s July weather normally sits in the low-to-mid 20s Celsius, with average highs around **23°C** and intermittent rain rather than a fixed pattern of heat or cool spells.[2][3] That means outcomes near the centre of the distribution are usually easier to model than sharp extremes, and a zero-priced outcome often reflects either an unusually narrow band or a view that the day’s peak is unlikely to finish exactly where the contract requires. If the broader summer pattern holds, traders will tend to anchor expectations around the day’s forecast high rather than the month’s average conditions.[2][3]

The main drivers to watch are the **local forecast updates**, especially any shift in the expected afternoon peak, cloud cover, or thunderstorms, because these can move the station maximum by several degrees. London heat alerts and forecast commentary can also matter when warmer spells build across the city, but the settlement itself depends on the **single highest reading** logged at London City Airport Station on the day, not on how warm London is more generally.[4] Traders also need to pay attention to the market’s own timing: the settlement window ends at **12:00 UTC**, so late-morning temperature swings remain relevant even if the day starts cool.[1]

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

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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 Prediction Market UK 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.