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 fall into one of several defined ranges. The settlement mechanism pulls directly from Wunderground's historical weather data for that specific station, which sits in East London and captures conditions across the airport's operational hours. The 0% crowd probability suggests either extreme confidence in a particular range or insufficient liquidity to establish meaningful odds across all buckets.

London's June temperatures typically peak between 20–24°C, with extremes occasionally reaching 28–30°C during heat waves. The Met Office's 30-year climate normals show a mean maximum of 21.5°C for early June, though the 1976 drought and 2022 heatwave both produced readings well above 30°C in the capital. Historical volatility matters here: a trader automating conditional orders would need to account for the wide spread between typical and anomalous outcomes, making range-based settlement more tractable than point estimates.

Catalysts to monitor include the North Atlantic Oscillation phase and upper-level ridge positioning in late May, which the Met Office publishes in its extended forecasts. The UK's seasonal transition into early summer typically brings Atlantic low-pressure systems, though blocking patterns occasionally allow continental air masses to dominate. Wunderground's historical archive updates daily through the settlement window, allowing programmatic verification of recorded highs without manual intervention—critical for automated settlement validation across multiple temperature buckets.

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

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 Polymarket App UK?

Zero. Polymarket App UK 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.

Do I need to KYC for this market?

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