Highest temperature in London on August 3?

Platform comparison

Market context

Polymarket is pricing this London City Airport temperature contract at **0% YES** today, so the market is effectively saying the chance of the day’s recorded high landing in the relevant Celsius band is being treated as negligible. On Polymarket, that view is expressed through USDC-backed conditional tokens on Polygon, so the price reflects what traders are willing to pay for exposure to the Wunderground-reported maximum at London City Airport rather than the broader London forecast.

That zero price sits against a pretty ordinary August backdrop rather than an extreme one. AccuWeather’s August outlook for London shows daily highs ranging from 67°F to 78°F, with an average high of 73°F, while several forecasts for 3 August point to warm conditions around the low 30s Celsius at peak but still with uncertainty around the exact station maximum and the final hourly profile.[1][3][7] Historical August norms for London also centre much lower, with average highs around 21°C, which helps explain why the market may be leaning towards a non-surge outcome even if the day looks warm by UK standards.[6][19]

For traders, the main catalyst is the intraday temperature path at London City Airport, not the citywide headline forecast. The contract cannot resolve until the settlement window closes at 12:00 UTC, so the highest reading later in the day still matters, and the Wunderground station history page is the key source for the final print. The practical watchlist is therefore the evolution of hourly heat, cloud cover, wind and any passing showers in east London, plus whether forecasters revise their midday maximums up or down as the day develops.[3][7]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on August 3? 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 Polymarket Alternative UK, which mirrors the Polymarket order book at 0% fees.

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

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

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.