Highest temperature in London on July 8?

Platform comparison

Market context

On 8 July 2026, the real-world event determining this market is the highest temperature recorded at London City Airport, measured in degrees Celsius. In prediction markets, a YES share pays out if the temperature falls within the specific range the market defines, while a NO share pays out if it falls outside that range. This market currently shows a 0% probability for YES, suggesting the crowd believes the temperature will not hit the target range, likely because early forecasts predict highs around 31–32°C, which is typical for mid-July but may be below the threshold set for this contract[1][5].

Historically, London’s July temperatures average 21°C but can spike significantly, with the highest ever recorded in the city reaching 40.2°C at Heathrow in July 2022[8]. While 32°C is a common peak for London City Airport in July, extreme heatwaves are rare and usually linked to specific atmospheric conditions like southerly winds and high pressure[1][4]. The current 0% probability implies the market expects a standard summer day rather than an outlier event, as recent data shows daily highs ranging from 71°F to 87°F (21–31°C) for July 2026[6].

Traders should monitor daily Met Office updates and Wunderground history for shifts in wind direction or pressure, as southerly flows can rapidly elevate temperatures[1][5]. A key catalyst is the scheduled release of the Met Office’s maximum temperature forecast, which currently cites a potential high of 35°C for the week, though this remains uncertain[5]. Any sudden announcement of a heatwave or changes in the southerly wind pattern, which is currently observed at 8 mph, could invalidate the current 0% probability and drive a sharp price correction[1].

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

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

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'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.

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 Prediction Market UK 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.