Highest temperature in London on July 15?

Platform comparison

Market context

The underlying event is the peak temperature recorded at London City Airport on 15 July 2026, measured in degrees Celsius and resolved via Wunderground history. With the crowd-implied probability for any specific range sitting at 0% YES, the market currently reflects a collective view that no defined bracket has yet attracted sufficient liquidity or conviction, a common state for weather markets before seasonal forecasts solidify.

Historically, mid-July highs in London typically range between 18°C and 28°C, with extreme outliers like the 40.2°C recorded in 2022 remaining rare anomalies rather than baseline expectations [2]. Programmatic traders often back-test these distributions against the Met Office’s long-term averages to calibrate conditional orders, noting that a 0% probability usually signals either a lack of data ingestion or a premature settlement window rather than a genuine impossibility of heat.

Key catalysts include the daily Met Office 5-day forecast updates and real-time pressure trends, which dictate whether southerly flows will push temperatures higher. Traders monitoring the settlement window ending 2026-07-15T12:00:00Z should watch for sudden shifts in humidity and wind speed, as the current 88% humidity and falling pressure at 1012mb suggest cooler, cloudier conditions that may suppress peak temperatures below historical extremes [2]. Automated bots often scrape these Wunderground feeds to trigger copy-trading strategies once the first hourly reading breaches a predefined threshold.

Sources: 1 · 2

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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.

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.

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.