Highest temperature in London on August 10?

Platform comparison

Market context

London’s high temperature will be set by the reading at London City Airport, with the market resolving on the highest value in Weather Underground’s Daily Observations table rather than the summary high/low box. The current crowd price is heavily skewed towards a mild outcome, with 27°C leading at 46% and 26°C close behind at 43%, which is a notable gap versus a 0% YES implied probability in the prompt data and suggests the market is not pricing any materially outside-range result.[1]

Historically, August 10 has produced some of London’s hotter readings, but the long-run context is that the city’s August maxima usually sit well below heatwave territory. London’s August record high is 38.1°C at Kew Gardens on 10 August 2003, while Heathrow reached 37.9°C that day; more recent August spikes have tended to cluster in the mid-to-high 20s or low 30s rather than the upper 30s.[5][8][11] That makes the present 26–27°C pair plausible by seasonal standards, and the narrow spread between those two bins is consistent with an analyst view of limited upside or downside from forecast uncertainty.[1][6]

For traders, the main catalysts are the local forecast for east London and any intraday update to observations at London City Airport before the settlement window closes. Polymarket’s own market page points to recent meteorological guidance around 27°C under sunny skies after a warmer prior day, which helps explain why the leading bands are packed tightly together.[1] Because resolution depends on the published Daily Observations table, late-day revisions to the station record can still matter until the next day’s first datapoint appears, so traders should watch the evolving station trace rather than the headline daily summary.[1]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on August 10? 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 UK, 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.

UK Frequently Asked Questions

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 UK. 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.

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.

What are the best prediction markets for UK traders in 2026?

For UKGC-regulated markets: Betfair Exchange (sports, politics) and Smarkets (sports, politics, lower commission than Betfair). For broader global event prediction: Polymarket (deepest liquidity, 0% fee, USDC settlement). For US-regulated option: Kalshi (USD, limited UK payment options). Most serious UK traders use a combination of Betfair for regulated sports and Polymarket for broader markets.