Highest temperature in London on June 23?

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Market context

On 23 June 2026, London City Airport will record its highest temperature for the day, a real-world event that this prediction market seeks to forecast by betting on whether the peak will fall within a specific Celsius range. In prediction markets, a YES share means you believe the outcome will occur (the temperature lands in the chosen range), while a NO share means you believe it will not; the current crowd-implied probability of 100% YES suggests traders are virtually certain the temperature will stay below the highest threshold offered.

Historical data frames this certainty, as London City Airport typically sees its warm season from mid-June to early September with average daily highs above 67°F (20°C), yet extreme heat days remain rare and often break records rather than repeat them[5]. Recent forecasts for 23 June predict a sweltering 93°F (34°C) with "extreme heat" warnings, while the Met Office lists Tuesday’s high at 35°C and Wednesday at 36°C, indicating a trend toward rising but contained temperatures rather than record-shattering spikes[2][6]. A 38°C peak in late June would break the June maximum record and is deemed abnormal by local observers, reinforcing the market’s confidence in lower ranges[9].

Traders should monitor live weather updates from Wunderground, the official resolution source, and watch for any sudden shifts in southerly wind patterns or humidity that could drive temperatures higher[3]. The Met Office’s hourly forecast already notes a potential 33°C rise in the next hour, suggesting volatility that could test the upper bounds of the 32°C–34°C ranges[6]. With no precipitation expected and abundant sunshine, the primary catalyst is the intensity of solar heating, which recent data shows is already pushing conditions toward "dangerous" levels for outdoor activities, yet still within the bounds of the current 100% YES probability[2].

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). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

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

Is this market available outside the US?

Prediction Market UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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 it cost to trade on Prediction Market UK?

Zero. Prediction Market UK routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.