Highest temperature in London on June 4?

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Market context

On 4 June 2026, the highest temperature recorded at London City Airport will determine which range this market resolves to, with settlement occurring at midday. The current crowd-implied probability of 0% suggests traders are pricing in a near-certainty that the day's peak temperature will fall below the lowest threshold offered, though the specific temperature bands available for this market remain undefined in the settlement criteria provided.

London's June weather historically clusters around 18–22°C for daily highs, with extremes rare but not unprecedented. The Met Office records show that temperatures exceeding 25°C occur roughly once every three years in early June, whilst readings above 28°C are exceptional for this period. The 0% probability across the board implies the market structure may contain only high-temperature ranges, or traders are heavily weighting the likelihood of unseasonably cool conditions. Comparable markets on UK temperature outcomes typically see meaningful divergence between sportsbooks (which rarely offer weather lines) and prediction-market pricing, though analyst consensus from the Met Office's seasonal outlooks remains the most reliable benchmark for June conditions.

Traders should monitor the UK's atmospheric setup from late May onwards, particularly jet-stream positioning and any Atlantic ridge development that could drive warm continental air into the British Isles. The Met Office issues monthly outlooks in early May that often signal whether June will trend warmer or cooler than the 30-year average. Any significant heatwave forecasts issued in the weeks preceding settlement would likely shift market probabilities substantially, though current pricing suggests little expectation of anomalous warmth on this specific date.

Methodology

We track Highest temperature in London on June 4? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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?

On Best Prediction Markets UK, 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.

Is this market available outside the US?

Best Prediction Markets UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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 Best Prediction Markets UK?

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

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Best Prediction Markets UK triggers a quick verification flow that finishes in minutes.