Highest temperature in London on July 10?

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Market context

London is currently locked in a significant heatwave, with the Met Office confirming temperatures hit 34C on Monday and remaining above 32C throughout this week. The 0% crowd-implied probability for a specific high-temperature range on July 10 appears to stem from a misunderstanding of the current forecast, which predicts Friday will still reach 32C before a gentle breeze offers slight respite. This is not a background anomaly but the immediate reality: forecasters expect peak temperatures to stay above 30C until at least Saturday, with the heatwave officially set to break only on Sunday when peaks drop to 29C.

Historical data frames this current probability as unusually low given recent trends. While London's average July high is typically 23C, the 2026 season has already seen eight days above 34C, including a record 35.1C in Wisley on 9 July. The UK Health Security Agency has issued amber heat alerts covering London from Wednesday through Sunday, reinforcing that sustained scorcher conditions are the norm rather than the exception. Traders should note that 2026 is statistically likely to experience at least one sustained period where temperatures climb well above 30C, making a 0% probability for a high-temperature threshold inconsistent with the active heatwave.

The primary catalyst to watch is the Met Office's Sunday forecast update, which signals the definitive end of this heat event. Traders must monitor the amber alert expiry at 9pm on Sunday, as the transition to cooler 29C peaks will be the key dependency for future temperature ranges. Recent reporting from Timeout confirms that while Friday cools slightly to 32C, the weekend will still arrive with highs of 30C under sunny skies. Any deviation from this forecast, such as an early onset of the cooling trend or unexpected thunderstorms mentioned in regional outlooks, would be the critical variable to reassess the market position immediately.

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Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Prediction Today, which mirrors the Polymarket order book directly.

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 Prediction Today. 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.