Highest temperature in London on May 26?

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Active sub-markets

Market context

The market concerns the highest temperature recorded at London City Airport on 26 May 2026, measured in degrees Celsius and resolved via Weather Underground's historical data for that specific station and date.

London's late May temperatures typically range between 15–22°C, though the airport station—situated on the Thames estuary—often records slightly cooler readings than central London due to proximity to water and maritime influence. Historical records from May 26 across recent decades show highs clustering in the 18–21°C band, with occasional outliers reaching 23–24°C during warmer springs. The 0% crowd probability suggests traders are pricing in either extreme confidence in a specific temperature band or uncertainty about which range the settlement will fall into once the day concludes.

Catalysts affecting the outcome include Atlantic weather systems and high-pressure systems tracking across the UK in late May. The Met Office's seasonal outlook and any significant weather warnings issued in the weeks preceding 26 May will signal whether conditions favour above or below-average temperatures for that date. Traders should monitor synoptic charts from mid-May onwards, as jet-stream positioning determines whether warm continental air or cooler maritime air dominates the south-east. The settlement depends entirely on Weather Underground's recorded maximum for the London City Airport station; readings from other London locations or airports will not apply.

Methodology

We track Highest temperature in London on May 26? 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

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 PolyGram, 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 PolyGram?

Zero. PolyGram 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, PolyGram triggers a quick verification flow that finishes in minutes.