Highest temperature in London on June 19?

Platform comparison

Active sub-markets

Market context

London City Airport’s maximum temperature on 19 June will be the settling print, so the key driver is not the citywide forecast but the station’s observed afternoon high. At the time of writing, the market is heavily clustered around the low 30s Celsius, with 31°C and 30°C the leading outcomes and 137.9k in volume, which suggests traders are pricing in a warm but still fairly bounded day rather than an extreme spike.[1]

For context, June temperature markets at this location have tended to move with forecast revisions rather than headline heat alone, because small changes in cloud cover, wind and shower timing can shift the day’s high by 1-2°C. Nearby weather reporting on the day has shown sunshine with a gentle breeze in the forecast, alongside observations that still include low-to-mid teens earlier in the day, which is consistent with an intraday rise into the high 20s or low 30s if clearing persists.[3][4] The current 0% YES reading is therefore best read as an accessibility artefact or a stale snapshot only if trading has already crystallised into one band; it does not match the live distribution shown elsewhere in the market.[1]

From a regulatory and tax-access angle, the relevant frame is that this is a weather-linked event market rather than a sports or financial contract, but users still need to consider jurisdictional limits. German GlüStV rules can treat many online gambling-style products as restricted or licensable in Germany, so access may be limited for German residents depending on platform settings and local classification. In the US, CFTC reach is the central issue because event contracts can be viewed as derivatives-like instruments, which can affect availability regardless of where the underlying weather is observed. “No-KYC up to $1,500” typically means a user can trade or withdraw within that threshold without completing full identity verification, which broadens access for small positions but does not remove jurisdictional restrictions or platform compliance checks.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 19? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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

Where can I trade this market with the lowest fees?

On Polymarket Tax UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 Polymarket Tax UK?

Zero. Polymarket Tax UK 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.

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.