Highest temperature in London on May 26?

Platform comparison

Active sub-markets

Market context

On 26 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges, measured in Celsius and sourced from Weather Underground's historical data for that specific station. The settlement window closes at midday, capturing the full daily temperature cycle. Across major prediction platforms, this market shows material divergence: Polymarket displays it with decimal odds and a 0% crowd probability, whilst Kalshi and Smarkets may quote equivalent ranges with different fee structures—Kalshi typically charging 2% on both sides versus Polymarket's variable maker-taker model. Betfair's exchange format allows lay positions unavailable on fixed-odds books, creating arbitrage opportunities for traders monitoring basis between platforms.

London's late May temperatures historically cluster between 18–22°C, with extremes rarely exceeding 25°C at City Airport, which sits on the Thames estuary and records cooler readings than central London. The Met Office's 30-year average for late May is 19.5°C; only three of the past two decades have seen daily highs above 24°C in this period. The 0% implied probability on Polymarket likely reflects algorithmic pricing on low-liquidity tails rather than genuine market conviction that extreme heat is impossible.

Traders should monitor the UK Met Office's extended forecast, typically issued five to seven days prior, and watch for Atlantic blocking patterns that occasionally drive warm continental air into southern England. Recent springs (2023–2025) have shown increased volatility in late-May temperatures, though no structural shift in the May 26 climatology itself. Liquidity across platforms remains thin; early positioning before late May forecasts solidify may offer value.

Methodology

This page compares Highest temperature in London on May 26? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

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 PolyGram, 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?

PolyGram 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.

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in minutes.