Highest temperature in London on July 27?

Platform comparison

Market context

London City Airport’s daytime high for 27 July will be read from Wunderground at the end of the settlement window, and Polymarket currently prices the contract at **70–71°F at 100%**, with the other listed range at **0%**. Because the market settles on the highest temperature recorded during the day, the last few hours before the window closes still matter for any late spike in the official daily maximum, even if the intraday trading view already looks fully one-sided.[1]

For context, London has a wide seasonal range in late July, and the market’s current pricing implies traders see a very narrow band as overwhelmingly likely rather than a broad distribution of outcomes. The relevant on-chain instrument is a set of conditional tokens traded against USDC on Polygon, so the price reflects collective positioning in a binary-style outcome set rather than a forecast of the exact Celsius figure.[1]

The main catalysts are straightforward: updates to the London weather pattern, especially any warm spell, southerly airflow or clear-sky period that can lift the airport reading into the afternoon. Reuters noted in a previous UK heatwave that Britain can move quickly into extreme-temperature territory when a wider European hot spell intensifies, which is the kind of pattern that can shift daily maxima materially.[2] Traders should watch the official Wunderground history page through the settlement window, since the market only resolves once the day’s data is finalised.[1]

Sources: 1 · 2

Methodology

We track Highest temperature in London on July 27? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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.

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 Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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 PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.