Highest temperature in London on August 10?

Platform comparison

Market context

London’s peak temperature on 10 August is being priced as a fairly tight call between the 26C and 27C brackets, which is why the market is effectively treating the day as a one-degree question rather than a major heat event.[1] The current crowd view sits at 0% YES overall only because the market is framed around a bracketed outcome, but within that frame traders are still clustering around the high-20s-for-London pattern that has been typical of warm August spells.[1][10]

Comparable London August cases suggest why a middling outcome is often the base case unless there is a sharp synoptic shift. Heathrow reached 36.4C during the August 2020 heat, but the more common mid-August highs in the capital sit well below that extreme, and London’s August record remains 38.1C at Kew Gardens on 10 August 2003, with Heathrow also touching 37.9C that day.[11][13] For this market, that history matters mainly as a reminder that London can overshoot quickly when hot air arrives, but absent a sustained heatwave the city more often settles into the mid-to-upper 20s.[7][12]

The main catalyst traders should watch is the live forecast and whether short-range model guidance keeps the city on the warm side through the afternoon, because the market resolves off the highest observed temperature in the Weather Underground daily observations table at London City Airport, not the summary high-and-low panel.[1] In practice, that means the decisive input is whether the day’s actual airport observations print a 26C or 27C maximum before the next day’s first datapoint appears; any late revision before that cutoff can still matter.[1] Recent reporting on UK summer heat has also shown how quickly a marginal forecast can become an unexpectedly hot London day when south-eastern temperatures build more strongly than expected.[13]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page tracks Highest temperature in London on August 10? across four political prediction venues. Live odds come from the Polymarket order book (the deepest political prediction-market book). Kalshi is the CFTC-regulated US alternative, Betfair the established UK sports-exchange with politics markets, Manifold the open play-money variant. For users geo-blocked from Polymarket directly, brokers like Trump Prediction provide a 0%-fee route into the same order book.

Resolution & payout

For political markets the resolution source is decisive. Polymarket defines a concrete source per contract (e.g. AP, Reuters, official electoral commission) and uses the UMA Optimistic Oracle as the on-chain dispute mechanism. With a clearly defined outcome the USDC payout lands within minutes of the final confirmation.

UK Frequently Asked Questions

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Historically more accurate than polls. Polymarket's Brier score on US 2024 elections was ~0.11 — better than 538 (~0.14) and every mainstream poll. Markets aggregate information with real skin in the game.

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Polymarket — by far. US 2024 presidential volume was ~$3.5B vs Kalshi (~$200M) and Betfair (~$120M). Where Polymarket is geo-blocked, brokers like Trump Prediction route into the same order book at 0% fees.

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It varies. They sit in legal gray areas in most jurisdictions. Polymarket is geo-blocked from US/UK/EU; some broker frontends have a different geo footprint. Trade only with capital you can afford to lose, and only if you understand the legal status in your jurisdiction.

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Yes. Betfair Exchange and Smarkets offer UKGC-regulated UK election markets (seat counts, party share, constituency results). Polymarket also lists UK election contracts with deeper global liquidity. Betfair winnings are typically tax-free for UK individuals; Polymarket profits are subject to HMRC CGT.