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 settlement will draw from Wunderground's historical weather database, which logs daily highs across all hours at that specific monitoring station. The 0% crowd probability suggests traders currently see no meaningful chance of an extreme outcome, though the market's resolution window extends to noon UTC on the settlement date, allowing for final data confirmation.

London's late May temperatures historically cluster between 18–24°C, with extremes rare but documented. The Met Office records show that May 31st highs have ranged from 15°C to 27°C over the past three decades, with the most recent decade trending slightly warmer. The current 0% reading likely reflects confidence in moderate outcomes rather than absence of volatility; late spring weather systems can still produce sharp swings, particularly if Atlantic low-pressure systems stall or continental air masses push northward. Comparable late-May events in 2020 and 2022 saw temperatures spike to 25–26°C within 48 hours of forecast shifts.

Traders should monitor the UK Met Office's extended outlook from mid-May onwards, particularly jet-stream positioning and any blocking high-pressure patterns developing over Scandinavia or the Atlantic. The Environment Agency's seasonal forecasts, typically issued monthly, will provide context for broader atmospheric conditions. Any significant warming pattern emerging in late April or early May could shift implied probabilities materially; conversely, persistent cool northerly flows would reinforce the current consensus toward lower ranges.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

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

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, Polymarket KYC UK 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.