Highest temperature in London on May 31?

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Market context

London's weather on 31 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 which temperature band will occur or treating this as a placeholder market pending clearer forecasting data as the date approaches. May's final day in London sits at the cusp of early summer, when high-pressure systems can occasionally push temperatures into the low-to-mid 20s, though cooler Atlantic systems frequently keep readings more modest.

Historical records from City Airport show May extremes have reached 27.8°C (in 2020), though such peaks remain uncommon. Most years see the month's highest temperatures cluster between 18–23°C. The specific resolution mechanism—using Wunderground's recorded maximum for the entire day—means even brief warm spells will register, whereas overcast or rainy conditions typical of English late spring would suppress readings. Traders should monitor long-range forecasts from the Met Office and European models beginning in late April, as these will provide the first reliable signals about whether high-pressure dominates or Atlantic lows prevail.

The settlement window closes at noon on 31 May, meaning morning temperatures won't affect resolution if afternoon readings prove higher. This timing advantage favours daytime heating patterns, which could push temperatures toward the upper end of typical May ranges if conditions align favourably. Current zero probability reflects genuine forecast uncertainty rather than consensus that cool weather is certain.

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 Prediction Today, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Prediction Today, 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, Prediction Today triggers a quick verification flow that finishes in minutes.