Highest temperature in London on July 27?

Platform comparison

Market context

London City Airport’s highest temperature on 27 July will be set by a single afternoon reading, and the market’s **0% YES** crowd price leaves the *favourite* side effectively unpriced rather than strongly wrong. The current consensus from live forecasts is for a fairly ordinary summer day: one recent forecast put London at about **25°C** with comfortable conditions and very low rain risk, which would sit well inside the lower-to-mid temperature bands rather than the hotter ranges needed for an outlier settlement.[3] In that sense, the market is leaning towards a **moderate underdog** outcome for anyone expecting a sharp heat spike at the airport station.

The historical frame is straightforward: London’s July average highs are around **23°C**, but the city can still see brief surges above **30°C** in hotter spells, with recent heatwave conditions showing how quickly the top end can move.[2] That matters because this contract is about the *day’s maximum* at London City Airport, not the average, so a brief sunny burst can matter more than the overall feel of the day. The value question is whether today’s forecast holds near the low-20s or whether a late-morning rise pushes into a higher band; on the available evidence, the consensus sits below the sort of extreme move that would make the upper temperature bins the clear favourite.[2][3]

For traders, the key catalysts are the updated short-range forecasts and any change in cloud cover, wind, or convective activity before the settlement window closes at midday UTC. Weather markets of this type usually turn on whether the day warms cleanly through late morning or gets capped early, so the practical watchpoint is not just the headline maximum but how quickly the temperature climbs at London City Airport specifically. If the forecast stays around the mid-20s, the market remains a contrarian angle against any late heat-build narrative; if models upgrade towards the low-30s, the pricing would need to re-rate fast.[1][3]

Sources: 1 · 2 · 3 · 4

Methodology

This page reviews Highest temperature in London on July 27? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win, which mirrors the Polymarket order book at 0% fees.

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?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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.