Highest temperature in London on June 30?

Platform comparison

Market context

The highest temperature recorded at London City Airport on 30 June 2026 will determine the outcome of this prediction market, which currently prices the YES contract at 0% on Polymarket. Traders using conditional tokens on the Polygon network, settling in USDC, see the market as effectively closed for the upper temperature ranges, reflecting a crowd consensus that extreme heat is improbable for this specific date and location.

Historical data frames this low probability: while the warm season at London City Airport typically begins around 16 June with average highs above 67°F, the station has rarely recorded temperatures exceeding 30°C in late June. Recent records show a UK June maximum of 36.7°C at a different site, but London City Airport’s observed high today is only 30°C, and yesterday’s maximum in Hampstead was 24.6°C, suggesting a cooler pattern than the heatwaves that drive higher-range bets [7][8][9].

Traders should monitor the Met Office’s 7-day forecast for London City Airport and any sudden shifts in pressure or wind direction, as these are the primary catalysts for temperature spikes [5]. The settlement depends entirely on Wunderground’s official daily high for EGLC, so any discrepancy between real-time observations and the final reported figure could alter outcomes, though current conditions show falling pressure and high humidity, which typically suppress peak temperatures [1][2].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi UK, which mirrors the Polymarket order book directly.

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

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 Kalshi UK 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.