Highest temperature in London on July 4?

Platform comparison

Market context

The real-world event at the heart of this market is the peak air temperature recorded on 4 July 2026 at London City Airport, measured in degrees Celsius. In prediction markets, a YES share pays out if the temperature falls within the specified range (here, 28°C or above), while a NO share pays out if it stays below that threshold. The current crowd-implied probability of 0% for YES suggests traders believe it is virtually impossible for the temperature to reach 28°C on that day, despite July being London’s hottest month on average.

Historically, London has seen extreme heat, with the highest ever recorded temperature being 40.2°C at Heathrow and St James’s Park in July 2022, though London City Airport typically records slightly lower peaks due to its urban location and coastal influence [8]. Average July highs at this station are around 22°C (72°F), and recent forecasts for July 2026 show daily highs ranging from 21°C to 31°C, making 28°C a plausible but not guaranteed outcome [7]. The 0% probability may reflect thin trading volume and the market’s short window, which can distort sentiment [2].

Traders should monitor daily Met Office and BBC Weather updates for London City Airport, as sudden shifts in cloud cover, wind direction, or humidity can dramatically alter peak temperatures [1][5]. A key catalyst is the official release of the day’s maximum temperature by Wunderground, which serves as the resolution source; any delay or discrepancy in this data could impact settlement clarity [2]. While no specific weather announcement is imminent, traders must watch for real-time observations showing southerly winds and high humidity, which often precede heat spikes [1].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Prediction Market 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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Prediction Market UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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.