Highest temperature in London on June 28?

Platform comparison

Market context

The highest temperature recorded at London City Airport on 28 June 2026 is the real-world event this market resolves, with the current crowd-implied probability sitting at 0% for any outcome above the baseline threshold. On Polymarket, this contract trades today with USDC on the Polygon network, where conditional tokens reflect the market’s near-zero confidence in a high-temperature spike, despite the date falling within London’s warm season.

Historical data frames this probability: the warm season at London City Airport runs from 16 June to 8 September, with average daily highs exceeding 67°F (19.4°C), yet extreme spikes remain rare. The hottest day of 2026 so far was recorded at Kew Gardens, southwest London, at 26.6°C (79.9°F), according to the Met Office [6]. However, London City Airport, situated closer to the Thames and urban core, typically records slightly lower peaks than western suburbs, and June 28 has not historically produced temperatures above 26°C in recent years [5].

Traders should monitor the Met Office’s 7-day forecast for London City Airport, which updates hourly and includes temperature, wind, and humidity warnings [7]. A key catalyst is the scheduled release of Wunderground’s daily data for 28 June, which will settle the market once the first data point is published [1]. Until then, the 0% probability reflects the lack of any heatwave announcement or extreme weather schedule for that date, with current conditions showing moderate humidity at 88% and falling pressure [2].

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 Polymarket Scam?, 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

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

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Scam? trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.