Highest temperature in London on August 15?

Platform comparison

Market context

On 15 August 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The market resolves using the Daily Observations table from Weather Underground rather than summary figures, a distinction that matters when intraday peaks diverge from official highs. For automated traders, this specificity means building a scraper that targets the correct data layer; pulling from the Day High & Low section would introduce systematic error.

August temperatures at London City Airport typically range between 20–24°C, with extremes occasionally reaching 28–30°C during heat waves. The 0% crowd probability suggests traders are pricing in either a very high threshold or scepticism about extreme heat occurring on that specific date. Historical August records for the station show that days exceeding 25°C are common but days above 28°C remain notable events; the current odds imply the market may be anchored to an unusually high temperature band. Reviewing past August patterns from the Met Office and comparing them to Wunderground's historical station data provides the baseline for calibrating position sizing.

Traders should monitor long-range forecasting models from mid-July onwards, particularly the European Centre for Medium-Range Weather Forecasts (ECMWF) and the UK Met Office's extended outlook. Heatwave alerts issued by the UK Health Security Agency typically precede sustained high temperatures by 5–10 days. For programmatic approaches, setting conditional orders tied to forecast updates—such as triggering buys if the 10-day ensemble mean exceeds 26°C—allows hands-off monitoring across the settlement window.

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 Kalshi Fees, which mirrors the Polymarket order book directly.

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 Kalshi Fees. 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.

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.