Highest temperature in London on June 23?

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Active sub-markets

Market context

The underlying event is the peak daytime temperature recorded at London City Airport on 23 June 2026, a date that historically sits at the start of the warm season with average highs above 67°F[4]. Current market odds of 99% YES suggest traders expect a near-certain outcome within a specific range, likely driven by the prevailing forecast of 33°C under sunny conditions[6]. This extreme probability mirrors similar markets where unsettled post-May weather patterns previously established a 17°C maximum with 100% certainty, indicating that when forecasts are clear, the book depth becomes heavily concentrated[1].

Traders should monitor the Met Office and BBC Weather updates for any shifts in the southerly wind flow or humidity levels, which currently sit at 88% and could influence the "feels like" temperature[2]. Recent commentary from weather experts notes that temperatures near 38°C are breaking June records and are not normal for late June, a catalyst that could drive volatility if the forecast adjusts[8]. The market's traction is directly tied to funding flows; as deposit fees via Klarna and withdrawal rails like SEPA become more efficient, capital moves faster into these weather books, deepening the liquidity around the 33°C frontrunner[6]. Any announcement regarding extreme heat warnings, which AccuWeather flags as dangerous for outdoor activities, will be the primary dependency for price movement[5].

Sources: 1 · 2 · 3 · 4 · 5

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

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

Where can I trade this market with the lowest fees?

On Polymarket Klarna 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.

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 Polymarket Klarna UK?

Zero. Polymarket Klarna UK 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.

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.