Highest temperature in London on June 26?

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Active sub-markets

Market context

On 26 June 2026, London City Airport will record its peak temperature for the day, a single real-world metric that determines the outcome of a prediction market currently implying zero probability for any YES range. This date sits within early summer, a period where London’s highs typically hover near 21°C, yet recent anomalies have pushed temperatures significantly higher. The market’s 0% implied probability suggests traders believe the temperature will fall outside all offered ranges, an unusual stance given the volatility of June weather in the capital.

Historical data frames this improbability: in 2026, Kew Gardens recorded 26.6°C on the hottest day so far, while London City Airport saw a high of 26°C on 24 June, just two days prior [3][4]. Even NW3 Weather noted a maximum of 35.7°C on 24 June, indicating extreme local variability [6]. These comparable cases suggest that a 0% probability is likely a mispricing, as June temperatures in London have already breached 26°C this year, making it plausible they could do so again on 26 June.

Traders should monitor the Met Office’s daily forecasts and any sudden shifts in wind patterns or cloud cover, which can drastically alter peak temperatures. The settlement relies on Wunderground data for London City Airport, meaning any discrepancy between station readings and regional forecasts could impact outcomes [4]. Recent news from Sky News confirms that southwest London has already tipped 26.6°C, a catalyst that underscores the risk of ignoring early summer heat spikes [7]. Platforms like Polymarket, Kalshi, and Betfair diverge here: Polymarket uses decimal odds with lower fees and no KYC, while Kalshi requires identity verification and offers implied probabilities, and Betfair uses a commission model on winnings, affecting how traders price this specific weather event.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in London on June 26? 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.

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.

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.