Highest temperature in London on July 9?

Platform comparison

Market context

The underlying real-world event is the peak temperature recorded at London City Airport on 9 July 2026, a date currently forecast as the week’s hottest with highs reaching 33°C before an unsettled pattern of rain and thunderstorms arrives later in the day. While historical July averages for London sit between 23–24°C, the current spell is markedly anomalous, with the Met Office reporting 34°C in the city earlier this week and 35.1°C recorded in nearby Surrey on 9 July, marking the eighth consecutive day above 34°C in the UK this year. This context explains why the market currently assigns a 50% probability to 34°C and 37% to 35°C, despite the crowd-implied 0% chance for any outcome below 30°C, reflecting collective confidence in the persistence of extreme heat.

Traders should monitor the timing and intensity of the forecasted rain and thunderstorms expected between midday and evening on 9 July, as these could significantly suppress peak temperatures if they arrive before the daily maximum is reached. The UK Health Security Agency’s amber heat alert, active from 9am on 8 July until 9pm on 12 July, underscores the official severity of the situation, while recent forecasts suggest peak temperatures will remain above 30°C until at least Saturday, 11 July, with the heatwave breaking only on Sunday. On-chain mechanics remain straightforward: USDC trades on Polygon using conditional tokens, with resolution hinging on the first data point published by Wunderground for 9 July, meaning any delay in data publication could postpone settlement beyond the 12:00 UTC deadline.

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Methodology

This page reviews Highest temperature in London on July 9? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.