Highest temperature in London on May 31?

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Market context

The settlement hinges on the highest temperature recorded at London City Airport on 31 May 2026, measured in Celsius and resolved via Wunderground's historical weather data. The 0% crowd probability reflects the market's current inability to price a specific temperature range, likely because the full range of possible outcomes has not yet been defined or the market interface requires clarification on available brackets.

May temperatures at London City Airport typically range between 15°C and 22°C, with historical highs occasionally reaching 25–27°C during warm spells. The UK Met Office records show that late May heat waves are uncommon but not unprecedented; the 2020 May period saw temperatures exceed 28°C across southern England on isolated days. Understanding the historical distribution of May extremes at this specific London location is essential for calibrating expectations, as microclimatic variations between City Airport and central London can shift readings by 1–2°C depending on wind patterns and urban heat effects.

Traders should monitor the Met Office's seasonal outlook for spring 2026 and any emerging climate patterns in late April and early May that year. The North Atlantic Oscillation and Atlantic jet stream positioning will influence whether high-pressure systems establish over the British Isles in late May, a prerequisite for temperatures exceeding seasonal norms. Real-time weather forecasts will become actionable only in the final week before settlement, though longer-range ensemble models from the European Centre for Medium-Range Weather Forecasts may offer directional signals two to three weeks prior.

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Best Prediction Markets UK, which mirrors the Polymarket order book directly.

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 Best Prediction Markets 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.

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'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, Best Prediction Markets UK triggers a quick verification flow that finishes in minutes.