Highest temperature in London on May 31?

Platform comparison

Active sub-markets

Market context

On 31 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The market currently prices all outcomes at 0%, reflecting that no single temperature band has attracted meaningful trading volume or conviction. Settlement hinges on Wunderground's historical weather data for that specific station, with the resolution window closing at midday UTC on the day itself. Traders holding conditional tokens representing their chosen range will see payouts determined by which bracket captures the actual recorded high.

London's late May temperatures typically cluster between 18°C and 24°C, though the city has recorded highs exceeding 28°C during late spring heatwaves. The 2022 May heatwave saw temperatures reach 29.5°C on 20 May, whilst more recent years have produced more moderate conditions. Historical volatility in spring weather patterns—driven by Atlantic pressure systems and occasional continental air masses—means outcomes spanning from cool (sub-18°C) to warm (above 25°C) remain plausible. The 0% crowd probability suggests the market lacks sufficient liquidity or participant interest to establish baseline pricing, rather than indicating genuine uncertainty about which range will resolve.

The UK Met Office publishes extended forecasts roughly two weeks ahead, with notable updates arriving in mid-May as the settlement date approaches. Any significant weather pattern shifts—such as a developing high-pressure system or Atlantic low-pressure intrusion—will likely trigger trading activity once forecasts solidify. Polymarket's USDC settlement on Polygon means traders can enter or exit positions continuously, though the thin current liquidity means early movers face wider spreads.

Methodology

We track Highest temperature in London on May 31? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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

Where can I trade this market with the lowest fees?

On Polymarket UK, 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 UK 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 does it cost to trade on Polymarket UK?

Zero. Polymarket UK 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.