Highest temperature in London on August 1?

Platform comparison

Market context

Polymarket is pricing this London City Airport reading at **0% for YES**, so the contract is effectively saying traders see no meaningful chance of a specified outcome clearing at the offered level, despite the market still being open on Polygon and settling in USDC through conditional tokens. The resolution is tied to the **highest temperature recorded on 1 August 2026** at London City Airport Station in Wunderground’s daily history page, so the relevant number is the day’s peak rather than an average or a noon reading.

For context, London is normally warm in early August, with Weather Spark putting 1 August within a typical range of about **60°F to 74°F** and Polymarket’s own description noting a strong crowd expectation around **26°C** for the day’s maximum. London’s record heat is far above that baseline: the city’s all-time high is **40.2°C** at Heathrow and St James’s Park in July 2022, while August records in the UK have reached the high 30s, including **38.5°C** in Faversham in August 2003 and **37.9°C** at Heathrow on the same day. That history matters for reading a temperature market: most August days cluster in the 20s Celsius, but a hot spell can still push outcomes several degrees higher.

A trader watching this contract would focus on forecast updates from the Met Office and any short-lived synoptic shifts that affect London’s daytime peak, especially sunshine, wind direction and cloud cover. The key dependency is whether a warm continental flow or a cooler Atlantic change arrives before the settlement window closes at **12:00 UTC**, because the Wunderground source uses the highest value recorded across the day at the station, not a fixed midday snapshot. On this structure, even a small forecast revision can matter because the contract resolves into temperature bands, so the final printed maximum at London City Airport is what counts.

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

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.