Highest temperature in London on July 23?

Platform comparison

Market context

London’s highest temperature on 23 July will be taken from London City Airport Station, and the market resolves to the temperature band containing the day’s peak reading rather than to an exact single number. At 4am UTC, Polymarket shows **26°C** as the frontrunner at **48%**, with **25°C** next at **24%**; that is the clearest available market signal for this contract, and it implies traders are leaning towards a warm but not exceptional summer day. [1]

The current **0% YES** crowd-implied probability is best read as a platform-specific quirk rather than a strong statement that the event is impossible, because the contract description says it cannot resolve until the day’s data are finalised. [2] Seasonal context also argues against treating a mid-20s Celsius outcome as unusual: London’s July average high is around **23°C**, with the month typically bringing several rain days and light to moderate winds, so a 25–26°C print sits above the norm but still within a plausible summer range. [3][4] On that framing, sportsbook-style pricing would usually cluster around the most likely temperature band rather than a binary yes/no view, while the prediction market is already pricing a modest premium for the upper end of the distribution. [1][3][4]

For traders, the main catalysts are the short-range forecast updates for London and any shift in cloud cover, wind, or rain timing that changes the daytime maximum at City Airport. The key dependency is the observed station reading rather than a citywide headline temperature, so a warm central London forecast can still miss if coastal influence, cloud build-up, or scattered showers suppress the airport’s peak. [2][3][4]

Sources: 1 · 2 · 3 · 4

Methodology

This page reviews Highest temperature in London on July 23? 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

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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.