Highest temperature in London on June 30?

Platform comparison

Market context

The real-world event this market tracks is the highest temperature recorded at London City Airport on 30 June 2026, measured in degrees Celsius and sourced from Wunderground. In prediction markets, a YES share pays out if the outcome matches the specified condition, while a NO share pays out if it does not. Here, the crowd-implied probability for a YES outcome is 0%, suggesting traders believe the temperature will not fall within the market’s defined range—likely because the expected high is either too low or too high for the resolution bracket.

Historically, late June in London often sees highs between 22°C and 28°C, with recent years recording peaks up to 35°C during heatwaves. For instance, on 24 June 2026, London reached 35.1°C, breaking records and prompting an extreme heat warning from the Met Office[7]. This context frames the current 0% probability as potentially premature, unless the market’s range excludes such high values. Traders should watch for official forecasts from the Met Office and BBC Weather, which have recently projected 17°C for early June under unsettled conditions[1], though late June typically sees warmer, more stable weather.

Key catalysts include daily Met Office updates, AccuWeather’s 10-day forecast for London City Airport, and any sudden shifts in wind patterns or cloud cover. Accuweather currently forecasts a high of 25°C (77°F) for 30 June, with intervals of clouds and sunshine[2]. The National Weather Service also notes rising temperatures through the morning, reaching 22°C by 8 AM[8]. Traders should monitor these sources closely, as deviations could significantly alter the probability landscape before the settlement window closes on 30 June 2026 at 12:00 UTC.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 30? 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

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

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.

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.