Highest temperature in London on June 27?

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Market context

The real-world event driving this market is the record-breaking heatwave currently sweeping the UK, with temperatures provisionally hitting 37.3°C at Santon Downham in Suffolk on 26 June, marking the third consecutive day of new June maximums[3]. Despite the current crowd-implied probability of 0% for the "YES" outcome, this figure appears starkly disconnected from the live market data on Polymarket, where 31°C is the frontrunner at 46% and 32°C follows at 37%, suggesting a significant pricing inefficiency or a misunderstanding of the settlement rules among the initial crowd[1].

Historical precedents for weather prediction markets often mirror the 50/50 jury and televote split seen in Eurovision, where expert panels and public sentiment diverge; here, the public crowd has likely misread the volatility of an unsettled post-May climate, whereas a jury of meteorological experts would recognise the 17°C daytime maximum recorded on 6 June as a baseline that has now been shattered by this extreme surge[2][3]. The cultural narrative momentum is firmly on the side of record-breaking heat, as thunderstorms and high temperatures have already caused delays at UK airports, reinforcing the likelihood of temperatures exceeding the 31°C threshold that the market currently undervalues[8].

Traders must watch the Met Office forecast updates for London City Airport, which currently indicate a maximum daytime temperature of 36°C, a figure that directly contradicts the 0% probability assigned by the crowd[3]. The primary catalyst is the official Wunderground settlement data for the London City Airport Station, which will be released after the settlement window ends, and any delay in this data release could prolong the pricing discrepancy[1]. Recent news from The Telegraph confirms that thunderstorms and high temperatures brought by this record-breaking heatwave have caused significant disruptions, serving as a tangible indicator that the 31°C range is not merely possible but probable[8].

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). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Is this market available outside the US?

PolyGram is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

What does it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in minutes.

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.