Highest temperature in London on August 5?

Platform comparison

Market context

London’s highest temperature will be set by the reading at London City Airport Station, with settlement based on the day’s peak value rather than the afternoon forecast alone. At 7am UTC, the market is already pricing a very tight cluster around the mid-20s: Polymarket shows **25°C** and **26°C** joint favourites at 36% each, with **24°C** next at 21%, while the contract’s current crowd-implied probability of 0% YES looks inconsistent with the listed outcome distribution and may reflect a stale or mislabelled reference rather than live pricing[1].

That pricing sits broadly in line with the published forecast range. Multiple weather sources point to a high near **25°C**, including a London forecast of 25°C with sunny intervals and mild temperatures, and a separate platform showing most models grouped between roughly **24.3°C and 25.7°C**[3][6]. The main historical context is that London’s August temperatures usually sit closer to the low-20s than the high-20s, so a mid-20s outcome is warmer than average but not extreme[10][14]. In market terms, that means the real disagreement is not over whether it will be warm, but whether the airport station briefly reaches 25°C or edges up to 26°C.

The key trader watchpoints are the timing of cloud cover, any weak frontal passage, and whether the warm air advects in quickly enough after the early-morning start to push the day’s high beyond 25°C[1]. Because the settlement source is Wunderground for London City Airport, the final print matters more than city-wide headlines: a narrow difference in airport-specific sunshine, wind, or sea-breeze influence can decide between adjacent ranges. The market also notes that revisions are considered until the first datapoint for the following day is published, so late updates to the station record can still matter for resolution[1].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on August 5? 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 Best Prediction Markets, 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

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.

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.

Do I need to KYC for this market?

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