Highest temperature in London on August 16?

Platform comparison

Market context

On 16 August 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The market resolves using the Daily Observations table from Weather Underground rather than summary figures, a distinction that matters when intraday peaks diverge from reported highs. For programmatic traders, this specificity means building a data pipeline that queries the correct endpoint; Weather Underground's API structure separates real-time station data from aggregated summaries, and resolution hinges on the former.

Historical August temperatures at London City Airport cluster between 20–26°C, with extremes reaching 28–29°C during heat waves. The current 0% probability assigned to the highest range suggests the crowd expects a typical or below-average August day. Comparable years—August 2022 saw 40°C across southern England, though City Airport recorded lower peaks—demonstrate how localised airport microclimates can dampen broader regional heat. Traders evaluating this market should cross-reference Met Office forecasts and seasonal patterns; August 2026 sits outside the typical peak heat window (July), and the airport's proximity to the Thames influences thermal dynamics differently than inland sites.

The key dependency is the Met Office's medium-range forecast window, which becomes reliable 10–14 days before the settlement date. Automated monitoring systems should flag any Atlantic weather systems or high-pressure ridges forecast to dominate mid-August 2026. Conditional orders tied to forecast thresholds—triggering buys if models show sustained 25°C+ scenarios—allow hands-on traders to position ahead of the crowd without constant manual checking.

Methodology

This page reviews Highest temperature in London on August 16? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Fees, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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.