Highest temperature in London on August 7?

Platform comparison

Market context

London’s high on 7 August is trading as a straightforward warm-day outcome rather than a heatwave event, with the crowd-implied 0% YES sitting well below most published forecasts. Recent London forecasts cluster around the mid-20s Celsius, including 26°C from one daily outlook and roughly 24.7°C to 26.7°C from multi-source forecast aggregation, while the Met Office says the south and south-east are seeing plenty of dry, sunny weather and temperatures climbing into the mid-20s.[2][4][7][11] That leaves the market well inside a range where a single degree matters, but not so hot that the contract is relying on an extreme afternoon spike.

Historically, London in August is usually comfortable rather than torrid: long-run summaries put average daytime highs around 22°C to 23°C, with forecasts for the month commonly showing highs in the low-to-mid 20s and only occasional pushes higher.[1][13][15] Compared with that baseline, a 26°C print is warm but not exceptional, and the current 0% implied price looks notably lower than the direction of travel in weather forecasts. The main cross-platform divergence is between the market and the forecast consensus: sportsbook-style weather lines are not given here, but the available analyst and model consensus is clearly above zero, and materially above an implied probability that suggests the market is pricing almost no chance of the relevant threshold being hit.[2][4][11]

Traders should watch the London City Airport observations feed, because this contract settles on the **Daily Observations** table rather than the headline day-high summary, so the exact recorded maximum matters more than the broader forecast.[11] The key catalyst is not a scheduled announcement but the actual afternoon temperature trace at the station, especially if sunshine persists longer than expected or if sea-breeze effects limit the peak. Because settlement closes at 12:00 UTC, any late-day heating after that point is irrelevant for the contract, which makes the morning-to-midday evolution the critical dependency.

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.