Highest temperature in London on August 3?

Platform comparison

Market context

The underlying event is the **maximum temperature at London City Airport on 3 August 2026**, with the market currently implying **0%** for the relevant YES outcome. In handicapper terms, that makes the favourite effectively the field, with consensus leaning hard towards a run-of-the-mill London summer reading rather than a standout hot spike; the value, if any, sits on the contrarian side only if the day turns notably warmer than the usual August profile.

That framing matters because London’s August averages are fairly restrained: AccuWeather’s monthly outlook shows daily highs mostly between **67°F and 78°F** and an average high of **73°F** (about **23°C**), while other August guides put typical daytime maxima closer to **22°C**. Comparable date-based forecasts for 3 August cluster around the low-to-mid 20s Celsius, with some models showing roughly **24°C** and only isolated higher-end scenarios reaching the low 30s, which is the sort of spread that keeps this market vulnerable to late model drift rather than early consensus certainty.

For traders, the key catalysts are the short-range forecast updates into the day, especially any shift in cloud cover, wind direction or rainfall risk that would cap the afternoon peak at the airport rather than in central London. Wunderground’s hourly and daily pages are the settlement reference here, so the live intraday evolution matters more than broader seasonal outlooks; the Met Office also notes that three-month outlooks are trend tools, not day-specific forecasts, which limits their value for a one-day temperature market.

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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 2026, 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

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 Who Will Win 2026. 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 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 2026 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.