Highest temperature in London on May 23?

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Active sub-markets

Market context

On 23 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The market currently shows 0% probability across all temperature brackets, suggesting either minimal trading activity or a technical settlement state. Polymarket prices this contract in USDC on Polygon, with conditional tokens issued for each temperature band; traders holding the winning range token at settlement receive their proportional payout once Wunderground's historical data confirms the day's peak.

London's late May temperatures typically range between 18–23°C, with occasional warm spells pushing toward 25°C. The Met Office's 30-year average high for 23 May sits around 20°C, though the city has recorded 28°C in late May during warmer years. The 2022 heatwave and subsequent warm springs provide recent reference points for how far above seasonal norms the temperature could deviate. Historical volatility in spring weather means the difference between a cool, cloudy day and an unseasonably warm one can span 8–10°C, making accurate range selection material to market pricing once trading activates.

The UK's weather forecast confidence typically extends reliably only 10–14 days ahead; traders will gain meaningful predictive advantage only as late May approaches. The Met Office's long-range outlook, updated monthly, will signal whether high-pressure systems or Atlantic weather fronts dominate the period. Any significant atmospheric pattern shifts announced in early May—such as Scandinavian blocking or tropical moisture incursion—could shift market expectations materially. Settlement finalises at 12:00 UTC on 23 May, giving traders the full calendar day to observe actual conditions before the window closes.

Methodology

We track Highest temperature in London on May 23? 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

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

Is this market available outside the US?

PolyGram 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.

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 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.

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.