Highest temperature in London on May 20?

Platform comparison

Active sub-markets

Market context

At London City Airport, the day’s maximum temperature on 20 May will be taken from the final, verified Wunderground history record for that station. The market is currently priced at 0% for a specific outcome, which is consistent with a market that has already absorbed a late-May London warm-up but still leaves room for a below-threshold reading if cloud, onshore flow, or a sea-breeze cap the peak. London’s May climate is usually mild rather than hot, with average highs in the low-to-mid teens Celsius, while station records show that late-spring spikes well into the 20s can still occur.

For context, London’s temperature distribution in May is skewed towards moderate highs, but the city has a long tail of warmer days and occasional sharp jumps when pressure rises and winds turn light. That means the market should be read less as a forecast of the month’s average weather and more as a binary on whether the airport station reaches a particular band at least once before the settlement window closes at 12:00 UTC. The relevant comparison is the local station history, not the broader London area, because airport readings can differ from central or suburban observations.

The main catalysts are the Met Office and other short-range model updates on the day, plus any change in cloud cover, wind direction, or precipitation timing that affects the afternoon maximum. A warm front arriving late, or sea-fret coming inland off the Thames estuary, would matter more than headline city-wide conditions. On access, this market is relevant under German GlüStV because it may be treated as gambling-like if offered to German users, while US CFTC reach can matter where a venue is seen as offering event contracts to US persons. “No-KYC up to $1,500” typically means small-volume access may be available without full identity verification, but that threshold can still be constrained by jurisdiction, payment rails, and platform checks.

Sources: 1 · 2 · 3 · 4 · 5

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 PolyGram, 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

Is this market available outside the US?

PolyGram is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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.

What does it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.