Highest temperature in London on August 5?

Platform comparison

Market context

London’s high at City Airport is set to be measured against a forecast that still leaves the market’s 0% yes price looking far below the weather consensus. The crowd is effectively treating the outcome as live rather than dead, but the front end of the book is clustered around **25°C and 26°C**, each on 36%, with **24°C** next at 21%[1]. That makes the favourite a warm but not extreme afternoon, while the underdog angle sits on either side of that band: a cooler-than-expected day around 23–24°C, or a slight upside pop into the mid-20s if sunshine is more persistent than expected[1][3].

Historically, London in early August usually sits in the low 20s, with long-run August daytime maxima around **22°C** and monthly averages near **18°C**, so a 25–26°C print is already a modest premium to climatology[10][12]. The current setup therefore favours the warm side of normal rather than a genuinely hot outlier, which helps explain why the market is concentrated in a narrow range instead of pricing a broad distribution[1]. The value question is whether the consensus has over-anchored on the forecast peak: if cloud, breeze or sea-breeze effects cap the day, the more defensive 24°C/23°C band can become the contrarian spot; if the warm advection verifies, 26°C has the cleanest upside versus the tie at 25°C[1][3].

For traders, the key catalyst is the live temperature evolution at London City Airport rather than any separate event schedule. Forecast coverage today points to sunny intervals and a 25°C high, with recent warm conditions already in place across London, including a 26.6°C reading at Kew Gardens earlier in the week[3][6][17]. That matters because late-morning cloud cover, wind direction and the timing of the day’s peak will decide whether the airport station edges above the consensus or stalls short; the market settles on the highest recorded temperature for the day, so a brief mid-afternoon spike is enough to flip the result[1].

Sources: 1 · 2 · 3 · 4 · 5

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.