Highest temperature in London on August 3?

Platform comparison

Market context

London’s 3 August maximum at City Airport looks like a **favourite for the upper temperature bands**, with the market showing **0% YES** despite day-ahead forecasts clustered in the low-to-mid 20s Celsius and some outputs pushing a hot peak around **29–33°C** inland. That leaves a clear consensus on “warm” rather than “mild”, but the value may sit in the higher bands if the airport’s urban setting captures a sharper afternoon top-end than the citywide average. [2][6][16]

Historically, early August in London sits close to the seasonal norm: AccuWeather’s August guide puts average highs at **73°F/23°C**, with forecast highs for the month ranging roughly **67°–78°F**. Comparable late-summer set-ups often settle in the low 20s Celsius, so a mid-20s resolution would fit the base case, while a low-30s outcome would be more of a **contrarian upset** and is typically where the underdog value lies if the forecast model overstates heat persistence. [1][16]

For traders, the main catalysts are the **hour-by-hour temperature path** and any shift in cloud cover, rain chance, or wind that could cap the daytime maximum before the settlement window closes at noon UTC. Wunderground’s hourly page for London on 3 August is the key live dependency for this market’s resolution source, and the available forecasts currently point to a sunny, dry day with very low rain risk, which supports a steady climb into the afternoon rather than an early stall. [2][4][6]

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 Who Will Win, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 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.