Highest temperature in London on June 25?

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Market context

London is currently experiencing a severe heatwave, with recent Met Office forecasts predicting daytime maximums near 35°C to 37°C at London City Airport, driven by persistent high pressure and southerly winds [1][3]. This extreme thermal activity frames the current 1% crowd-implied probability for the highest temperature outcome, as historical data shows June 25 typically sees averages well below 30°C, yet the ongoing anomaly has pushed recent readings to 33.9°C on June 23 alone [2][8]. Traders should view the low probability not as a dismissal of heat, but as a market bet against the specific upper threshold required to win, given that even 31°C carries a 25% chance and 30°C holds 27% in parallel markets [1].

The primary catalyst for this market is the final 24-hour temperature sweep from Wunderground, which will confirm the peak reading before the settlement window closes at 12:00 UTC on June 25 [1]. Traders must monitor real-time updates from the Met Office and BBC Weather, which currently indicate a Thursday maximum of 31°C with a feel-like temperature of 34°C, alongside a 30% chance of rain at 6am that could suppress peak temperatures [3][4]. Any sudden shift in wind direction from the current southerly flow or an unexpected increase in cloud cover could prevent the temperature from reaching the necessary threshold, making the next few hours critical for resolving the 1% probability [4]. The market remains entirely dependent on this single data point from the airport station, with no secondary verification sources available to alter the outcome.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on June 25? across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at Sport Prediction — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

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 Sport Prediction, 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?

Sport Prediction 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.

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.