Highest temperature in London on May 26?

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Market context

London's weather on 26 May 2026 will be measured against historical May temperatures at City Airport, where late-spring conditions typically range between 15–22°C. The 0% crowd probability suggests traders are either uncertain about the specific temperature bands available or treating this as a calibration exercise ahead of the settlement window closing at midday on the day itself. Recent shifts in seasonal patterns mean late May in London has become less predictable; the past three years saw May highs vary from 19°C to 26°C depending on Atlantic weather systems and high-pressure positioning over the UK.

Comparable May days at City Airport show that temperatures above 25°C occur roughly once every two to three years during this month, typically when continental air masses push northward or when a prolonged ridge of high pressure establishes itself. Below-average May temperatures (under 16°C) are less common but do occur when cool northerly flows dominate. The Met Office's seasonal outlooks and European ensemble forecasts will be the primary drivers of trader conviction in the weeks leading up to 26 May; any shift toward warmer or cooler signals could trigger significant probability movement.

Traders should monitor the UK Met Office's extended outlook updates (issued weekly) and any notable Atlantic weather pattern changes signalled by the North Atlantic Oscillation index. The resolution depends entirely on Wunderground's historical data from London City Airport Station, making real-time weather station accuracy the final arbiter. Settlement occurs at noon on the day, giving traders only a morning window to adjust positions once actual conditions become visible.

Methodology

We track Highest temperature in London on May 26? 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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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.

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.

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.