Highest temperature in London on May 23?

Platform comparison

Active sub-markets

Market context

On 23 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The settlement hinges on Wunderground's historical weather data for that specific date, measured in Celsius. London's May temperatures typically range between 12°C and 22°C, though anomalies occur; the record high for May in the capital stands at 29.9°C, set in 2008. The current 0% crowd probability suggests traders are either awaiting clearer seasonal forecasts or treating this as a placeholder market pending activation closer to the event date.

Historical May weather patterns in London show considerable year-to-year variance. The past decade has produced May highs ranging from 18°C to 26°C at comparable monitoring stations, with late-May days generally warmer than early-month readings. The 2022 heatwave that pushed UK temperatures above 30°C occurred in June and July, not May, establishing a useful precedent for how exceptional heat typically arrives later in the season. Traders should note that spring weather forecasting beyond four weeks carries substantial uncertainty; current meteorological models will sharpen considerably in late April 2026.

From a regulatory standpoint, this market's accessibility depends on jurisdiction and deposit thresholds. Under German GlüStV rules, prediction markets operating without a licence face restrictions on marketing to German residents. US CFTC oversight applies to derivatives-style contracts; weather prediction markets structured as binary or range-based contracts may fall outside direct CFTC reach if properly categorised as non-financial prediction instruments. Many platforms permit participation up to $1,500 without full KYC documentation, though this threshold varies by operator and regulatory interpretation. Traders should verify their own platform's compliance framework before committing capital.

Methodology

We track Highest temperature in London on May 23? 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

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

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.

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.

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, PolyGram triggers a quick verification flow that finishes in minutes.