Highest temperature in London on August 2?

Platform comparison

Market context

The relevant event is the highest temperature recorded at London City Airport on 2 August, and the contract is currently priced as if a **27°C** peak is the most likely outcome, with the crowd assigning it **52%** and **26°C** at **26%**; by contrast, the market is effectively dismissing a very hot outcome, with **28°C** down at **18%** and the listed 0% yes reading far below the live market’s dominant line. The Polymarket board is therefore not treating this as a binary heatwave bet, but as a narrow-temperature-distribution call around the upper-20s, which matters because one degree either side of the modal forecast can reshuffle the winner under this contract’s range-based settlement.

Historically, London summer temperature markets tend to cluster around the low-to-mid 20s unless a stable high-pressure set-up locks in clear skies and light winds, in which case the distribution shifts up by a degree or two rather than exploding higher. That is the frame for reading the current pricing: the forecast set is centred on the **27°C** area, which lines up with comparable weather expectations that London’s August highs usually sit below the high-20s, while recent UK heat has shown that brief surges can push readings into the low 30s without making them the modal outcome for a specific city station. In cross-platform terms, the sportsbook-style weather forecasts and analyst consensus are closer to the upper-20s band than to anything extreme, so the key divergence is not direction but how much weight each venue gives to a one-degree swing around 26–28°C.

The main catalysts are the day’s cloud cover, any late-morning sea-breeze influence, and the exact timing of the warmest air over east London before the settlement window closes. Met Office guidance cited by Polymarket points to strengthening high pressure, light winds and southerly flow, which supports the 27°C centre of gravity, while broader August forecasts for London also place daily highs in the mid-to-upper 20s rather than far above them[1][2][4]. Traders should also watch for any revised station observations, because the market notes that changes are considered until the first datapoint for the following date is published, which can matter if the afternoon peak is registered or amended late[1].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on August 2? 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 PolyGram. 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 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.