Highest temperature in London on June 4?

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Market context

On 4 June 2026, London City Airport's weather station will record a daily maximum temperature in Celsius. The Polymarket contract currently prices all temperature ranges at zero, reflecting minimal trading activity rather than genuine certainty about the outcome. Settlement hinges on Wunderground's historical data feed for that specific station, with the resolution window closing at midday UTC on the settlement date itself—a tight constraint for traders seeking last-minute information.

London's June temperatures typically range between 15°C and 22°C, though heat waves occasionally push readings into the mid-to-high 20s. The 2022 heatwave saw London exceed 40°C in early July, demonstrating the city's vulnerability to extreme heat during summer months. However, early June historically sits before the warmest period of the year. City Airport, located in the Isle of Dogs, records slightly different conditions than central London due to its proximity to the Thames and urban heat island effects. Recent years show June 4th temperatures clustering around 18–20°C, with outlier years reaching 24–25°C.

Traders should monitor the Met Office's medium-range forecasts as June approaches, particularly any signals of early-season high-pressure systems or Atlantic weather patterns that could drive anomalous warmth. Climate oscillations like the North Atlantic Oscillation influence UK weather weeks in advance. The settlement mechanism's reliance on a single airport station means localised conditions matter; cloud cover, wind direction, and tidal influences on the Thames all affect readings. Any forecast issued in late May suggesting an unseasonable warm spell would likely shift market pricing substantially from its current dormant state.

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

Where can I trade this market with the lowest fees?

On Kalshi 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?

Kalshi 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.

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.

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.