Highest temperature in London on June 19?

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Market context

The real-world event hinges on the peak temperature recorded at London City Airport on 19 June 2026, a date that sits squarely within the city’s warm season which typically begins around 16 June. Historical data shows that while London can reach extremes, with the highest ever observed being 40.2 °C at Heathrow in July 2022, mid-June temperatures at EGLC usually hover between 18 °C and 25 °C. The current crowd-implied probability of 0% for any specific high range suggests the market is pricing in a near-certainty that the temperature will fall outside the offered brackets, likely because the expected range is too narrow or misaligned with typical June climatology where daily highs average above 67°F [4].

A power-user approaching this programmatically would monitor live feeds from Wunderground and the Met Office, setting conditional orders to trigger if the temperature breaches 23 °C, a threshold that has been exceeded in past comparable cases. Traders should watch for immediate weather announcements, particularly the forecast of scattered showers tapering off late afternoon which could suppress peak temperatures, as noted in current forecasts showing a 90% probability of rain [2]. Recent updates from the Met Office indicate a daily high of 23 °C with 88% humidity, a dependency that directly influences the settlement outcome and should be factored into any algorithmic trading strategy [7]. The settlement window ending in 2026 requires precise timestamping of data ingestion to ensure the highest recorded value for the day is captured accurately.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket App UK, which mirrors the Polymarket order book directly.

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?

Polymarket App 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.

What does it cost to trade on Polymarket App UK?

Zero. Polymarket App 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.