Highest temperature in London on July 13?

Platform comparison

Market context

London City Airport is forecast to reach a high of 27°C today, with sunny conditions and a moderate southerly breeze, setting the baseline for the market resolving on whether the peak temperature exceeds a specific threshold implied by the 3% YES probability. The crowd heavily favours the 27°C outcome at 52%, with 26°C as the next likely result at 25%, suggesting consensus lies firmly in the mid-to-high twenties rather than extreme heat [2].

Historically, July is London’s hottest month, averaging a high of 22°C (72°F), though record extremes have pushed past 40°C, such as the 40.2°C spike at Heathrow in July 2022 [1][5]. The current 3% implied probability for the YES outcome appears undervalued if the forecasted 27°C is exceeded by even a degree, as the market’s narrow weighting on 27°C leaves little room for volatility; a contrarian angle would target outcomes above 28°C, where value may sit if southerly flow intensifies.

Traders should monitor real-time updates from Wunderground and Met Office forecasts, particularly any shifts in wind direction or humidity that could push temperatures higher [4][2]. The Met Office currently lists a maximum feels-like temperature of 24°C, but BBC and The Weather Network both cite a high of 27°C, indicating a tight margin where a 1°C swing could alter settlement [4][6][7]. No official announcements are pending, but atmospheric dependencies—especially pressure falling and humidity at 88%—remain key catalysts for temperature deviation [6].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on July 13? 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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 Who Will Win. 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.

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 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.