Highest temperature in London on June 28?

Platform comparison

Market context

On 28 June 2026, London City Airport is experiencing sunny intervals with a high of 26°C, yet the crowd-implied probability for any temperature outcome above the lowest range sits at 0% YES, a stark contrarian signal that defies the day’s warmth. Historical data frames this anomaly: last year’s heatwave pushed London to 35.1°C, and the hottest June ever recorded hit 36.4°C, while climatological norms for late June typically see highs above 20°C. The consensus is locked on the lowest temperature bracket, likely due to a misinterpretation of the settlement window or an overreliance on early-season models, creating a clear value spot for traders betting on the 20–25°C range.

Traders must watch the Met Office’s extreme heat warnings and the National Weather Service’s real-time METAR updates for London City Airport, as these dictate the official resolution via Wunderground. A recent Met Office alert extended red extreme heat warnings until Thursday evening, signalling potential for temperatures to breach 30°C if cloud cover clears rapidly. The key catalyst is the afternoon wind shift from the south, which could advect warmer air from the continent, a dependency that current models may have underweighted. With the settlement window ending at 12:00 UTC on 28 June 2026, any late-morning temperature spike could invalidate the 0% consensus, offering a high-value contrarian angle for those betting on the 25–30°C bracket.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 28? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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 Who Will Win. 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 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 Who Will Win trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.