Highest temperature in London on June 26?

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Market context

London is currently experiencing a severe heatwave, with temperatures soaring to 36°C today at the London City Airport, marking one of the hottest June days in recent history[1]. The Met Office has forecasted maximum daytime temperatures reaching 37°C for the coming period, significantly exceeding the seasonal average of 26°C for late June[1]. This extreme thermal event is driven by a persistent southerly flow bringing warm air from continental Europe, with humidity levels at 88% and falling pressure indicating unstable conditions[2].

Historical data frames the current 0% crowd-implied probability for lower temperature ranges as highly questionable, given that recent years have seen June highs consistently breach 30°C[4]. Just two days prior, on 24 June 2026, the NW3 Weather station recorded a maximum of 35.7°C, while London Heathrow Airport hit 33.9°C, setting the hottest June day in the UK since 1976[6][9]. The warm season, which officially begins on 16 June, typically sustains average daily highs above 67°F (25°C), making a sub-25°C peak exceptionally unlikely under these current atmospheric conditions[4].

Traders must monitor the settlement window ending at 12:00 UTC tomorrow, as the official resolution relies on Wunderground data for the highest temperature recorded at London City Airport[1]. Key dependencies include the timing of the daily peak, which NW3 Weather noted occurred at 16:47 BST on 24 June, suggesting the maximum may not be captured if the settlement closes before the afternoon heat spike[9]. No major cooling announcements or weather system shifts have been reported by the BBC or Met Office, reinforcing the likelihood of sustained high temperatures through the settlement deadline[2].

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

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 PolyGram, 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.

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 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.

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.