Highest temperature in London on August 7?

Platform comparison

Market context

The key event is the highest **actual temperature** recorded at London City Airport and reported in Weather Underground’s Daily Observations table on 7 August, not the headline daily high. On the evidence available, the market’s **0% YES** crowd price looks far below both recent London summer conditions and the live forecast set-up, which is the sort of gap that usually reflects either mispricing or a very specific range expectation rather than a broad view on the day’s weather.

For context, London in August typically sits in the low-to-mid 20s Celsius, but forecast outputs for this date cluster around the mid-20s, with one London forecast showing about **26°C** and another monthly view putting the day near **24–25°C**.[1][4] Trading history in comparable temperature contracts suggests the market often settles in the bucket nearest the observed airport maximum, so the practical question is whether the reading lands around 24–25°C or pushes up into 26–27°C; Zyntra’s contract snapshot showed most interest concentrated in **25°C** and **26°C** ranges rather than the tails.[3]

The main catalyst is the intraday Weather Underground observation feed itself: London City Airport data can differ from city-centre forecasts, and this market resolves off the recorded maximum in that station’s Daily Observations table, which can lag or diverge from summary-style forecast pages.[3] Traders should also watch any late-day warmth from the broader UK heat pattern noted in recent reporting, with forecasters warning of a renewed spell of hotter conditions across southern England later in the week.[12]

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 Kalshi vs Polymarket, 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 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.