Highest temperature in London on June 28?

Platform comparison

Market context

The real-world event in question is the peak daytime temperature recorded at London City Airport on 28 June 2026, a metric that will determine the settlement of a specific prediction contract. Current crowd-implied probability for the "YES" outcome sits at 0%, suggesting traders view the specific temperature range as virtually impossible, yet this divergence clashes with the 39% probability assigned to 24°C on the adjacent 30 June contract and the 34% volume backing 25°C for the 28 June date on other platforms[1][2].

Historical precedents frame this low probability as potentially premature, given the UK recently smashed a century-old temperature record twice in 24 hours, with 35°C recorded at Kew Gardens and Heathrow during the 2026 European heatwaves[7][10]. Furthermore, a separate 32.2°C reading was logged in Kew and Heathrow earlier in June 2026, surpassing the previous 29.4°C record from 2025, indicating that London’s thermal ceiling is significantly higher than the 0% market implies for this specific date[9].

Traders must monitor the Met Office daily high forecasts, which currently project a maximum daytime temperature of 26°C for London City Airport, alongside real-time Wunderground data that will serve as the official resolution source[4]. The settlement window ends at 12:00 UTC on 28 June, creating a dependency on the precise timing of the peak heat, while recent restrictions on alcohol in the city during the heatwave period suggest heightened public and official attention to temperature spikes that could influence market liquidity[10].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on June 28? 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 PolyGram, which mirrors the Polymarket order book at 0% fees.

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

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.

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.

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.

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.