Highest temperature in London on August 3?

Platform comparison

Market context

Polymarket is pricing the London City Airport Station maximum for 3 August at **0% YES**, with the contract settled in USDC on Polygon through conditional tokens, so the current market is effectively saying the day will not land in the listed temperature band that pays out. The practical question for traders is not whether London will be warm in general, but whether the single highest observation recorded at EGLC by Wunderground before the settlement window closes falls into the relevant Celsius bucket.

That 0% print is notably lower than the surrounding weather context. Near-term forecasts for London are pointing to a warm early-August day, with forecast highs mostly in the low-to-mid 20s Celsius and some private forecast services showing values closer to the upper 20s or low 30s Celsius, while the broader August climate norm sits around the low 20s Celsius to low 20s Fahrenheit equivalents depending on source presentation.[1][2][4][14][17] For a range-based market, the key distinction is that airport readings can differ from central-London forecasts, and the eventual settled value comes from the station’s observed daily maximum rather than a citywide average.[15]

Traders should watch the intraday London forecast updates, any shift in cloud cover or rainfall timing, and whether the heat signal persists through the afternoon, because those factors determine the top reading before the 12:00Z settlement cut-off.[2][4][5][19] The main dependency is the Wunderground history page for London City Airport itself, since that source governs resolution and can diverge from headline city forecasts.[4]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on August 3? 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.