Highest temperature in London on May 22?

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Active sub-markets

Market context

London’s peak temperature on 22 May is being set by a late-spring warming trend rather than by any political calendar, and the contract resolves against the highest reading at London City Airport. With the market currently priced at 0% for the yes side, it is effectively saying there is no live chance of an outcome in the upper part of the range; in practice, late-May London often sits in the low-to-mid teens Celsius, while hotter outcomes depend on a clear, settled airmass and enough daytime heating to lift the city above the seasonal norm.

That baseline matters because London’s May climatology is mild, but not uniformly cool. WeatherSpark shows average highs rising through the month from about 16°C to 19°C, with readings above the mid-20s uncommon rather than impossible. Historical records underline the tail risk: London’s broader May maximum record is 32.8°C, and recent extremes such as the 40.2°C national record in July 2022 show how quickly the UK can overshoot when hot air arrives. For this market, the comparable case is not the monthly average, but whether a short-lived warm spell peaks during the airport’s observation window.

The main catalyst traders should watch is the final daytime forecast cycle and any Met Office or Wunderground update for London City Airport, because the settlement source is the station’s final daily high rather than a citywide average. AccuWeather’s monthly outlook points to highs broadly in the low 20s Celsius for late May, but short-range revisions will matter more than seasonal guidance. If a ridge builds over southern England, the market can move quickly on a warmer noon-to-afternoon forecast; if cloud, sea breezes or showery flow persist, the ceiling stays lower and the contract should remain anchored to the more moderate ranges.

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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 May 22? 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.

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 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.