Highest temperature in London on August 19?

Platform comparison

Market context

The market is pricing the highest temperature at London City Airport on 19 August 2026 at 0% probability across all temperature bands, suggesting the crowd expects either no trading activity or a systematic underpricing of likelihood. August in London typically sees daily highs between 20–24°C, with extremes occasionally reaching 28–30°C during heat waves. The 0% crowd probability indicates either extreme confidence in a specific narrow range or insufficient liquidity to establish meaningful odds.

Historical August temperatures at London City Airport show that days exceeding 25°C occur roughly once every two to three years during the summer month, whilst readings above 28°C remain rare events tied to continental high-pressure systems. The UK's record August temperature of 38.5°C (set in 2003) remains an outlier; more typical hot Augusts peak in the 26–27°C range. This baseline suggests the market may be underweighting moderate-to-warm outcomes that fall within historical norms rather than extreme scenarios.

Traders should monitor the Met Office's seasonal outlook for summer 2026 and any emerging climate pattern forecasts from spring onwards. The North Atlantic Oscillation and Atlantic Multidecadal Oscillation influence UK summer temperatures; persistent high-pressure systems over the continent in mid-August could drive temperatures toward the upper end of the historical distribution. Weather Underground's Daily Observations table—the specified resolution source—occasionally records slightly different highs than summary displays, so familiarity with that platform's data structure will matter at settlement.

Methodology

We track Highest temperature in London on August 19? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.