Highest temperature in London on July 7?

Platform comparison

Market context

On 7 July 2026, the London City Airport Station will record its peak temperature for the day, a single data point that determines the outcome of a prediction market with a current crowd-implied probability of 0% for any YES outcome. This near-zero pricing suggests the market expects the temperature to fall outside the defined resolution range, likely because historical July highs at this location typically exceed the threshold in question. For a power-user evaluating tooling, the approach is programmatically straightforward: fetch the daily maximum from Wunderground’s API at 12:00 UTC on 8 July, then compare it against the range brackets. The historical context is critical; July is London’s hottest month, with an average high of 22°C (72°F) and frequent spikes above 30°C, as confirmed by the Met Office and Weather Spark[4][5]. Recent data from today shows a high of 31°C, reinforcing that 0% probability is likely a mispricing if the range includes temperatures below 30°C.

Traders should monitor the UK Met Office’s daily forecast updates and the National Weather Service’s real-time METAR feeds for London City Airport, as these provide the most reliable pre-settlement indicators[3][5]. A key catalyst is the scheduled release of the UK’s summer heatwave warnings, which often precede temperature spikes above 32°C; the BBC’s 14-day forecast for London City Airport currently shows moderate humidity and falling pressure, conditions that can amplify heat retention[1]. For conditional order strategies, the dependency is the Wunderground data feed’s latency at settlement; any delay could trigger a copy-trading bot to execute late. The most recent news source, the AccuWeather July 2026 forecast, predicts daily highs ranging from 21°C to 31°C, with overnight lows between 13°C and 20°C, suggesting the market’s 0% probability may be overly conservative if the range includes 25–30°C[8]. Programmatic traders should script a cron job to poll Wunderground every 15 minutes post-settlement to capture the exact peak.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on July 7? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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 Polymarket Review UK. 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'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.