Highest temperature in London on May 25?

Platform comparison

Active sub-markets

Market context

London's weather on 25 May 2026 will be recorded at City Airport, with the highest temperature that day determining which range this market settles into. The UK Met Office typically issues seasonal outlooks in April, and spring temperature forecasts become more reliable within two weeks of the event itself. Historical data from the same station shows May highs in London cluster between 18–22°C in cooler years and 24–28°C during warmer spells, though extremes above 30°C are rare that early in the season.

The 0% crowd probability reflects genuine uncertainty rather than consensus that heat is impossible. May 2026 sits too far ahead for deterministic weather models, which lose skill beyond 14 days. What matters for traders is monitoring the Atlantic Oscillation index and sea-surface temperature anomalies in the North Atlantic from March onwards—these drive whether high-pressure systems stall over the UK or Atlantic lows dominate. The Met Office's long-range bulletin, published monthly, will narrow the range as spring progresses.

For traders managing deposits and withdrawals on polymarket-klarna.co.uk, liquidity in weather markets typically deepens as settlement approaches and model consensus solidifies. SEPA transfers and Klarna payment rails process fastest when volume concentrates in the final week before resolution. Early positions carry wider spreads; late entries benefit from tighter books but face reduced time to exit if conditions shift unexpectedly.

Methodology

We track Highest temperature in London on May 25? 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 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.

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 does it cost to trade on PolyGram?

Zero. PolyGram 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.

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.