Highest temperature in London on June 17?

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Market context

On 17 June 2026, the highest temperature recorded at London City Airport will determine the settlement outcome, with resolution sourced from Wunderground's historical weather data for that specific station. The market currently shows 0% implied probability across all temperature ranges, suggesting either insufficient liquidity or a technical display issue rather than genuine consensus that no temperature will be recorded.

London's June weather historically clusters around 18–23°C for daily highs, with extremes rare but documented. The Met Office records show that temperatures above 25°C occur in roughly one in three Junes, whilst readings exceeding 28°C are infrequent. The 0% crowd probability appears misaligned with climatological norms; even conservative forecasting would assign non-trivial probability to ranges covering 20–26°C. This disconnect may reflect low trading volume or early-stage market formation rather than substantive weather intelligence.

Traders should monitor the UK Met Office's long-range forecast updates in May and early June, which typically refine confidence intervals for specific dates. European weather patterns—particularly Atlantic ridge positioning and North African heat transport—become clearer 10–14 days ahead. Any significant heatwave signals from extended forecasts would shift probability mass toward higher temperature ranges. Settlement depends entirely on Wunderground's recorded data for London City Airport (EGLC), making station-specific conditions relevant; urban heat effects and airport microclimates can produce readings 1–2°C above surrounding areas during calm, sunny conditions.

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — are listed with their platform attributes, because they operate off-chain and a 1:1 comparison of contract mechanics isn't possible.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

FAQ

Where can I trade this market with the lowest fees?

On BTC Prediction, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

BTC Prediction 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.

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 BTC Prediction?

Zero. BTC Prediction 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.