Highest temperature in London on July 24?

Platform comparison

Market context

London’s highest temperature will be set by the reading at London City Airport on 24 July, with settlement based on the day’s maximum Celsius value from the Wunderground history page. With the crowd currently pricing **0% YES**, the market is effectively saying no traded expectation has yet formed around a specific high-temperature band, which is a meaningful divergence from the kind of weather pricing seen on other London temperature contracts where probabilities are often distributed across several adjacent outcomes rather than pinned to zero.

For context, July in London is usually a mild-summer month rather than a heat-extreme month, with typical daytime highs around the low-20s Celsius and frequent rain interruptions. Recent July 2026 coverage has shown that London can still swing into brief hot spells, with the Met Office cited as recording **34C** earlier in the month and forecasting highs in the low- to mid-30s during the July heatwave, before conditions eased again. That history matters because this contract is about the single highest reading at one station, not the day’s average, so even a short-lived afternoon spike can decide the band.

The main catalysts are the short-range weather models, Met Office updates, and any heat-health or thunderstorm alerts that change expectations for the airport station before midday settlement. For cross-platform comparison, sportsbook-style weather lines typically move only when a heat event becomes widely expected, while prediction markets can stay thin or mispriced until late forecast revisions; here, the 0% crowd price suggests the market has not yet incorporated a clear consensus. Analysts generally treat London City Airport as somewhat less extreme than inland sites because of its urban and estuarine setting, but that difference is small on days with a broader south-east England heat plume.

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). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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 Best Prediction Markets. 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.

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.