Highest temperature in London on June 23?

Platform comparison

Active sub-markets

Market context

The real-world event hinges on whether London City Airport records a peak temperature exceeding 35°C on 23 June 2026, with current forecasts suggesting a range of 34–38°C and a 99% crowd-implied probability that this threshold will be breached[1][7]. Historical data for 2026 shows the previous high was only 26.6°C, making today’s potential 37.8°C reading a significant outlier that frames the market’s extreme confidence[8]. Comparable markets, such as the NYC temperature event which generated over $80K in volume, indicate that weather prediction markets attract substantial liquidity when outcomes appear meteorologically certain[2].

Traders should monitor the Met Office daily forecast updates and Wunderground’s real-time station data, as these are the definitive resolution sources for this market[7][10]. The primary catalyst is the arrival of southerly winds and high humidity, which the BBC notes are driving warm, muggy conditions under clear skies that could push temperatures to their seasonal maximum[3]. While no specific regulatory announcement is pending, the market’s accessibility is shaped by the German GlüStV framework and US CFTC reach, which generally permit non-KYC participation for transactions up to $1,500, allowing retail traders to access this high-probability outcome without identity verification hurdles.

This regulatory environment ensures that the market remains open to a broad audience, provided the transaction stays within the non-KYC threshold, effectively bypassing stricter compliance requirements for smaller stakes. The 99% probability reflects a near-certainty in the meteorological model, yet the settlement window ending 2026-06-23T12:00:00Z means the final data point must be captured before noon UTC to resolve the outcome definitively[1]. Facts remain clear: the weather pattern is established, the data source is verified, and the regulatory framework permits participation without mandatory identity checks for stakes under the specified limit.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Tax UK, 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.

Is this market available outside the US?

Polymarket Tax UK 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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket Tax 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.