Highest temperature in London on July 5?

Platform comparison

Market context

The real-world event in question is the highest temperature recorded at London City Airport on 5 July 2026, measured in degrees Celsius. While one prediction market currently shows a 0% implied probability for the "YES" outcome, this starkly diverges from Polymarket, where traders assign a 47% chance to 29°C and 44% to 28°C, with significant volume on 26°C and 30°C as well [1][2]. Analyst consensus from the Met Office and BBC forecasts daytime highs of 29–31°C under settled conditions, directly contradicting the zero-probability stance of the other platform [3].

Historically, July is London’s hottest month, with an average high of 72°F (22°C) at this station, though recent years have seen peaks well above this baseline [8]. Current observations today show a high of 28°C with clear skies, suggesting the atmosphere is primed for warmth rather than the cold implied by the 0% market [4][5]. The divergence between the zero-probability contract and the active 29°C frontrunner on Polymarket highlights a critical pricing inefficiency for cross-platform arbitrage.

Traders should monitor the Met Office’s seven-day forecast updates and Wunderground’s real-time data releases as the settlement window closes [6]. Any sudden shift in southerly wind patterns or humidity levels could alter the peak temperature, as humidity is currently high at 88% with falling pressure [5]. The resolution depends entirely on the first data point published for 5 July 2026 on Wunderground, making the timing of that upload a key dependency for market settlement [2].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on July 5? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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 vs Polymarket. 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.

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 Kalshi vs Polymarket trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.