Highest temperature in London on August 3?

Platform comparison

Market context

Polymarket is pricing this London City Airport temperature contract at **0% YES**, so the market is implying no chance of a qualifying high for 3 August 2026, even though the event is still live until the midday UTC settlement window closes. The contract settles on the **highest temperature recorded in Celsius** at London City Airport Station on that date, so traders are effectively holding a USDC-backed position on a single observation in Polygon-based conditional tokens rather than on London weather in general.

For context, London in August is normally a mild summer market, with average highs around the low 20s Celsius and forecast ranges in the low-to-mid 20s across major weather sites for early August 2026. AccuWeather shows August daily highs in London ranging from **67°F to 78°F** this month, while several forecasts for 3 August cluster around **21°C to 24°C**, with some models pushing higher into the high 20s or low 30s.[1][2][4][14][17] That means a 0% price is not a statement that the day will be cool; it is a statement that the current crowd sees no material path to the specific airport reading landing in a YES range.

The main catalysts are the next few forecast updates for east London, especially any shift in cloud cover, wind direction, or marine influence affecting London City Airport rather than central London. Wunderground’s hourly forecast for London indicates a warm day with a high around **83°F** and intervals of cloud and sunshine, which would be consistent with a firm upper-end reading if sustained into the afternoon.[4] Traders watching the contract will also care about whether later updates from competing forecasters preserve the warm spell or trim the peak, because the settlement depends on the *highest* observation before noon UTC on the source page, not the day’s headline city forecast.[5][15]

Sources: 1 · 2 · 3 · 4 · 5

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 PolyGram, 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

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.

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.

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.