Highest temperature in London on May 20?

Platform comparison

Active sub-markets

Market context

Polymarket is pricing this London City Airport temperature contract at 0% for the market’s YES side, so the current book is effectively saying the recorded 20 May maximum is already a settled no-higher-thannumber outcome. On Polymarket, users post USDC on Polygon and buy conditional tokens tied to the London City Airport reading; the contract resolves to the Celsius band containing the day’s highest temperature once Wunderground finalises the history page for EGLC. For a trader, the key point is that the on-chain price reflects the market’s read on the airport station, not a citywide average or a Met Office summary.

Contextually, late-May London maxima usually sit well below the sort of spikes that only appear during brief warm spells. AccuWeather’s May forecast for London put daily highs mostly in the low-to-mid 20s Celsius, while Met Office commentary this spring has shown how quickly southern England can jump above 20°C when skies clear, before cooler Atlantic air returns. That means this kind of contract is less about seasonality alone and more about whether a short-lived warm plume aligns with the specific observation window at London City Airport. Even a broadly warm day can miss a higher bracket if cloud, wind off the Thames, or an earlier peak limits the airport station reading.

The immediate catalysts are the day’s actual weather evolution and any late-day shift in cloud cover, sea breeze, or frontal timing around London, rather than scheduled announcements. Traders should watch the Wunderground history page for eventual finalisation, and any Met Office updates that alter the expected afternoon maximum. Because the settlement window ended at 12:00 UTC on 20 May, the key dependency is no longer forecast direction but the official observation trail that confirms the highest temperature recorded before noon at the airport station.

Sources: 1 · 2 · 3 · 4 · 5

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

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'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.

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.