Highest temperature in London on August 1?

Platform comparison

Market context

London’s highest temperature on 1 August is usually a mid-to-high 20s Celsius affair, and that matters because the market resolves at London City Airport rather than central London. Seasonal references put early August near the warmest part of the year, with typical 1 August highs around 60–74°F and August averages in London near 23°C, but the airport reading can sit a little below city-centre hotspots.[2][8] On the current book, Polymarket shows a heavy clustering around **26°C**, with **25°C** the main alternative, while 27°C and above are priced much lower.[4] That profile is broadly consistent with the crowd-implied **0% YES** on the contract as offered here, because the market is a narrow temperature-range question rather than a simple hot-day bet.

Historical context points to why the downside and upside are both limited. London’s August record highs are extreme outliers, with the UK August maximum record at 38.5°C and London-area records around 38°C in exceptional heatwaves, but those events are rare and usually associated with widespread national heat alerts.[7][15] By contrast, recent August days have often topped out in the low-to-mid 30s at London airports only during notable hot spells, such as 36.4°C at Heathrow in August 2020 and 34.7°C at St James’s Park during a 2025 heat peak.[9][16] For a settlement on London City Airport’s daily maximum, a result around 25–26°C would be the market’s consensus-style base case, with materially hotter bins needing a clear synoptic shift.

Traders should watch the final UK forecast updates and any last-minute model moves tied to high pressure, cloud cover and wind direction, because those are the main drivers of whether the day lands at 24–25°C, 26°C, or pushes higher. The contract also depends on the Wunderground daily history entry for London City Airport and only settles once the day’s data is final, so any late revision to the station record can matter.[3] Compared with sportsbook-style temperature lines, the prediction-market pricing is much tighter and more event-specific, and analyst consensus appears to favour a modest, non-extreme outcome rather than a pronounced heat spike.[1][4]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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.

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 PolyGram 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.