Highest temperature in London on July 27?

Platform comparison

Market context

Polymarket is pricing the London City Airport temperature contract at **100% for 70-71°F** and **0% for 65°F or below**, so the market is effectively locked into a mild-summer outcome rather than a wider dispersion of outcomes.[1] Because settlement depends on the **highest temperature recorded at London City Airport Station** on the day, traders are really buying exposure to the final Wunderground daily high in **USDC on Polygon**, with the payout determined by the matching **conditional token** bucket rather than the exact peak on the chart.[1]

For context, London has shown that exceptional heat can break through normal summer expectations when conditions line up: the U.K. reached a provisional **40.2°C at Heathrow** during the 2022 heatwave, underlining that airport stations can post extreme readings when hot air masses settle over south-east England.[2] That makes the current 0% implied price for the lower band meaningful only as a live market view, not a statement that the weather cannot surprise; a short, sharp spike near the early afternoon can still matter if it lands in the final Wunderground range for the station.[1][2]

The key catalyst is the day’s **actual maximum temperature at London City Airport**, which is what Wunderground’s daily history page will use once the reading is finalised, and Polymarket notes the market cannot resolve until all data for the date is complete.[1] Traders should watch for updates from the airport station feed and any broader London weather pattern changes, especially sunshine, wind direction, and convective showers, since these can shift the daytime high by a degree or two and move the settlement bucket even when the contract already looks heavily one-sided.[1]

Sources: 1 · 2

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket Alternative UK, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Alternative UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Alternative UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.