Highest temperature in London on August 20?

Platform comparison

Market context

This market resolves on the highest temperature recorded at London City Airport on 20 August 2026, using the Daily Observations table from Weather Underground as the primary source. The settlement window closes at midday UTC on that date, capturing the full diurnal temperature cycle up to noon.

London's August temperatures have historically ranged between 18°C and 32°C, with the city's record high of 40.3°C set in July 2022. August typically sees average highs around 23–24°C, though heat waves can push readings into the high 20s or low 30s. The 0% implied probability suggests the market is pricing in either an unusually cool August or uncertainty about which specific temperature band will be recorded. Historical volatility in summer weather patterns—including the influence of Atlantic pressure systems and occasional continental heat advection—means August temperatures in London remain genuinely variable year to year.

Traders should monitor long-range weather forecasts released in late July and early August 2026, particularly from the Met Office and European Centre for Medium-Range Weather Forecasts, which typically show skill in predicting temperature ranges 10–14 days ahead. The North Atlantic Oscillation and sea surface temperature anomalies in the Atlantic will influence whether August 2026 develops anticyclonic conditions favouring heat or cyclonic patterns keeping temperatures moderate. Real-time observational data from Weather Underground's London City Airport station will be the decisive factor; any discrepancy between that source's Daily Observations table and summary figures will favour the former for resolution purposes.

Methodology

Political prediction markets differ structurally from sports betting: thinner liquidity, longer settlement windows, higher sensitivity to single news events. This page shows the live Polymarket quote for Highest temperature in London on August 20? plus platform attributes for the three reference venues, so you can see at a glance where the deepest market for this question sits.

Resolution & payout

Political markets typically settle on official candidate or agency confirmation. Polymarket uses UMA Optimistic Oracle: a proposer posts the outcome with a bond, the two-hour window opens, then the smart contract pays USDC.

Kalshi settles USD via CFTC clearinghouse, with clearly defined resolution sources (e.g. AP race calls for elections). Betfair settles after the official outcome is registered with the league or agency. Manifold is play-money.

UK Frequently Asked Questions

What resolution source is used for elections?

Polymarket defines the source per contract — usually Associated Press (AP Race Call), Reuters or the official electoral commission. The source is stated in contract details before the market opens.

Which platform has the deepest political liquidity?

Polymarket — by far. US 2024 presidential volume was ~$3.5B vs Kalshi (~$200M) and Betfair (~$120M). Where Polymarket is geo-blocked, brokers like Trump Prediction route into the same order book at 0% fees.

Are political prediction markets legal in my country?

It varies. They sit in legal gray areas in most jurisdictions. Polymarket is geo-blocked from US/UK/EU; some broker frontends have a different geo footprint. Trade only with capital you can afford to lose, and only if you understand the legal status in your jurisdiction.

Why do Polymarket and Kalshi differ on elections?

Kalshi must follow CFTC compliance — strict definitions, clear resolution sources, US citizens only with KYC. Polymarket operates globally without CFTC oversight — deeper liquidity, but also higher regulatory risk.

Are UK election prediction markets available from the UK?

Yes. Betfair Exchange and Smarkets offer UKGC-regulated UK election markets (seat counts, party share, constituency results). Polymarket also lists UK election contracts with deeper global liquidity. Betfair winnings are typically tax-free for UK individuals; Polymarket profits are subject to HMRC CGT.