Highest temperature in London on May 28?

Platform comparison

Active sub-markets

Market context

On 28 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges, with settlement determined by Wunderground's historical weather data for that specific station. The market currently prices all temperature brackets at 0% YES across Polygon, suggesting either extreme illiquidity or a technical issue with conditional token pricing rather than genuine uncertainty about whether temperatures will occur. Traders holding USDC on Polygon can enter positions once liquidity normalises, with payouts determined by which bracket captures the day's peak reading in Celsius.

London's May temperatures historically cluster between 18–24°C, with the airport station recording occasional peaks near 26–28°C during settled high-pressure systems. The 28 May 2025 maximum was approximately 20°C; the preceding five years show May highs ranging from 17°C to 25°C at this location. Unusually warm or cool springs shift these distributions materially—the 2022 May heatwave saw peaks above 27°C across the South East, whilst cooler springs typically cap out around 19–21°C. Current pricing reflects no meaningful differentiation between likely and unlikely outcomes, making this a calibration opportunity once the market's conditional token mechanics settle properly.

The Met Office issues extended forecasts from mid-May onwards; traders should monitor their 25–31 May outlook for high-pressure positioning and Atlantic weather patterns. Bank holidays and weekend timing carry no direct weather impact, though forecasting confidence typically improves within seven days of the settlement window. Historical Wunderground data for EGLC (London City Airport's ICAO code) provides the sole authoritative source, so cross-checking current station functionality ahead of late May remains prudent for position sizing.

Methodology

We track Highest temperature in London on May 28? 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

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 UK?

Zero. Polymarket 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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket 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.