Highest temperature in London on June 13?

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Active sub-markets

Market context

On 13 June 2026, the highest temperature recorded at London City Airport will settle this market into one of several temperature bands. The resolution hinges on a single daily maximum reading from Wunderground's historical data for that specific station, which sits in East London and typically records slightly warmer conditions than central London due to its location near the Thames estuary. The 0% crowd probability suggests traders are either uncertain about the outcome distribution or have not yet engaged with this particular weather contract.

London's June temperatures have historically ranged between 18°C and 28°C, with the long-term average high around 21°C. The Met Office records show that temperatures exceeding 25°C occur in roughly one-third of June days, whilst readings above 28°C remain uncommon but not exceptional. The current flat probability across all temperature bands reflects the inherent difficulty in predicting a specific day's maximum six months in advance, though seasonal patterns and climate data provide a baseline. Kalshi and Betfair have historically offered tighter spreads on European weather contracts than some competitors, whilst Polymarket's fee structure and decimal odds presentation may appeal differently to traders comparing cost-per-trade across platforms.

Traders monitoring this contract should track the UK Met Office's seasonal forecasts released in April and May 2026, which will narrow confidence intervals as the date approaches. Atlantic weather patterns, particularly the North Atlantic Oscillation, influence June temperatures across the UK; any signals of unusual warmth or coolness in May forecasts will likely shift implied probabilities. Real-time weather model updates from ECMWF and GFS in early June will drive the sharpest repricing closer to settlement.

Methodology

We read Highest temperature in London on June 13? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live quote comes directly from the Polygon order book; the other three are listed with their platform attributes — fees, KYC, settlement currency, payment options — because a 1:1 contract comparison without API access would be guesswork.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Alternative, 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?

Polymarket Alternative 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 Polymarket Alternative?

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