Highest temperature in London on June 4?

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Market context

The highest temperature recorded at London City Airport on 4 June 2026 will determine the resolution bracket for this market. London's June weather typically ranges between 15–22°C, though heat waves can push readings into the upper 20s or low 30s. The settlement hinges on the single daily maximum recorded by the Wunderground station at this location, which sits in East London near the Thames.

Historical June records for the London area show that temperatures exceeding 28°C occur roughly once every five to seven years during early summer. The Met Office's 30-year climate averages place the mean maximum for early June at approximately 19°C, with the 90th percentile around 24°C. Comparable years—such as June 2022, which saw highs of 24–26°C across London—provide useful benchmarks for assessing the probability distribution across available brackets. The 0% crowd probability suggests traders are pricing in below-average conditions or uncertainty about the specific station's microclimate.

Traders should monitor the extended forecast from the UK Met Office and BBC Weather in the weeks leading to 4 June, as these sources update long-range outlooks for high-pressure systems or Atlantic weather patterns that could drive temperatures upward. Any official heat-health alerts issued by the UK Health Security Agency would signal elevated risk of higher readings. The specific location at City Airport, positioned near water, may record slightly cooler maxima than inland London sites, a factor worth accounting for when comparing historical data from other monitoring stations.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

On Sport Prediction, which mirrors the Polymarket order book at 0% 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 it cost to trade on Sport Prediction?

Zero. Sport Prediction routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.