Highest temperature in London on May 28?

Platform comparison

Active sub-markets

Market context

London's highest temperature on 28 May 2026 will be recorded at City Airport Station and resolved against historical data from Wunderground. The settlement window closes at midday UTC, meaning the full 24-hour temperature range for that date must be captured before resolution. For automated traders, this creates a straightforward data-pull scenario: Wunderground's historical archive provides structured daily highs, making conditional orders feasible once the date passes and the station's readings are published.

May temperatures in London typically range between 15–22°C, though the historical record for late May sits considerably higher. The 28 May 1944 recorded 29.4°C at Greenwich, whilst more recent decades show occasional peaks near 25–26°C during warm spells. The current 0% crowd probability suggests traders are either awaiting forecast data or treating this as a placeholder market pending clearer seasonal patterns. Late-May weather in the UK remains volatile; high-pressure systems can drive temperatures into the mid-20s, but cool Atlantic systems frequently suppress readings into the mid-teens.

The Met Office publishes extended forecasts roughly two weeks ahead, with meaningful updates arriving seven to ten days before 28 May. Traders should monitor early-June pressure patterns and any anomalous warming signals from late April onwards, as these drive May's thermal trajectory. The Wunderground data source is reliable for historical verification but requires manual confirmation that readings are attributed to the correct station code (EGLC), as London has multiple weather stations with varying microclimates.

Methodology

We track Highest temperature in London on May 28? 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

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 Bot 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.