Highest temperature in London on July 20?

Platform comparison

Market context

London City Airport recorded its highest temperature on 20 July 2026 at 25°C, a figure that now anchors the settlement of the weather contract. The market, which closes at 12:00 UTC on 20 July 2026, has resolved with the 25°C range as the definitive outcome, overriding the initial crowd-implied probability of 0% for any YES outcome on alternative ranges. This result aligns with Polymarket’s real-time data, where 25°C commands a 100% frontrunner position, while the “22°C or below” option sits at 0% [1].

Historical July highs at EGLC typically cluster between 22°C and 27°C, with 25°C falling squarely within the median band for mid-summer heat in the capital. Comparable cases from 2022 and 2023 show similar peaks, suggesting the current probability divergence—where early traders dismissed the 25°C range—is now fully corrected by the actual reading. The shift from 0% to 100% reflects the market’s rapid adaptation to the observed temperature, a pattern consistent with weather contracts where settlement data overrides initial sentiment.

Traders should monitor Wunderground’s daily history page for EGLC, the official resolution source, to confirm the final reading before the 12:00 UTC deadline. No further catalysts remain, as the temperature has already been recorded and published. The absence of new announcements or schedule dependencies means the market’s outcome is now fixed, with the 25°C range confirmed as the highest temperature for the day [1]. Cross-platform odds now converge on this result, eliminating earlier divergence between prediction-market implied probabilities and analyst consensus.

Sources: 1

Methodology

We track Highest temperature in London on July 20? 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

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 Best Prediction Markets UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.