Highest temperature in London on June 21?

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Market context

London City Airport’s highest temperature on 21 June 2026 is the real-world figure this market will settle on, measured in Celsius and taken from the day’s peak reading on Wunderground’s daily history page. A **YES** share pays out only if the final recorded maximum lands in that share’s specified temperature range; a **NO** share pays if it does not, so the market is really a way of pricing how likely each band is, not just whether the day is warm or cool. [1]

For context, late-June London typically sits near the low 20s Celsius, so a reading in the high 20s or above would be meaningfully warmer than average. Current market pricing has treated those hotter bands as the main possibilities, with 29°C and 30°C the leading outcomes in the live order book, which helps explain why a 0% YES price can still coexist with active trading in several temperature ranges. That sort of setup usually reflects the market’s view that one of the listed bands is overwhelmingly likely, rather than an expectation of zero heat. [1][5]

The main thing to watch is the airport observation itself, because this contract depends on the highest temperature published for London City Airport on the resolution source, not on forecasts or city-wide averages. Forecast updates from the Met Office and BBC Weather can still matter before the reading is locked in, especially if they point to a short-lived afternoon peak or cloud and rain suppressing temperatures; in this market, the final settlement is determined only after the source posts the first data point for the following date. [4][7][1]

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

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?

Prediction Market UK 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.

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 it cost to trade on Prediction Market UK?

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

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Prediction Market UK 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.