London in mid-May typically experiences temperatures between 15 and 20 degrees Celsius, making a high of exactly 12°C unusually cool for late spring. This market exemplifies the precision required in weather prediction trading: hitting an exact temperature is vastly more difficult than predicting a range. The 0% current odds reflect trader consensus that precisely 12°C is highly improbable for May 17, 2026. Resolution depends entirely on the official high temperature recorded by the UK Met Office at their London weather station. The specificity of this market reveals how nuanced weather trading can be—a single degree matters enormously. Even slight variations in atmospheric circulation patterns, cloud cover timing, or wind direction can push the actual high above or below the 12°C threshold. Traders are pricing in the low probability of this exact outcome, though the market remains active with modest volume and liquidity. Historical May weather patterns in London rarely produce highs at precisely round temperatures; most days cluster around 17-18°C in normal years. Until close of day on May 17, when official temperature readings determine settlement, traders can adjust positions based on real-time weather developments.
What factors could move this market?
Exact-temperature weather markets sit at the intersection of forecasting precision and statistical improbability. London's May climate typically reflects the transition from spring into early summer, with diurnal ranges (difference between daily high and low) averaging 8-10 degrees Celsius. A high of exactly 12°C would require either an unusually strong cold system to persist through midday, or anomalously weak solar radiation, or both. Historically, London experiences such cool highs roughly 5-8% of the time in May, but hitting a precise value is far rarer—perhaps 1-3% of days match any single exact temperature prediction. The current 0% odds suggest traders believe May 17, 2026 will not be that day, incorporating both climatological priors and short-range forecast consensus. Recent spring patterns over the UK have trended warmer than historical norms; the past three Mays averaged 2-3 degrees above the 30-year mean. This warming bias tilts odds further away from 12°C, a comparatively cool outcome. Weather systems pushing conditions toward the YES case would include: a deep Atlantic low migrating northeast across the UK, overcast skies reducing daytime heating, cool maritime air masses, or northerly winds channeling polar air southward. Conversely, factors supporting the NO case (the current market favorite) are far more numerous: high pressure dominating northwest Europe, clearing skies allowing robust daytime warming, southwesterly flow bringing mild Atlantic air, and the simple fact that any temperature between 13°C and 19°C (the typical May range) would resolve the market against 12°C. The wide bid-ask spread and thin volume reflect the market's extreme specificity—only traders with strong conviction about May 17's exact conditions are active. Met Office forecast models, updated hourly, will drive sentiment shifts in the hours leading to settlement. Temperature measurement standardization matters too: the UK Met Office uses Stevenson screens at specific elevations, so microclimatic variation across London's neighborhoods is irrelevant to resolution. Even marginal model adjustments toward cooler scenarios could generate buying interest in YES, though reaching exactly 12°C remains statistically unlikely given the breadth of alternative outcomes.
What are traders watching for?
Met Office forecast updates May 17 morning; model consensus toward cooler systems would shift odds from current 0% baseline
Atlantic synoptic pattern: track of low pressure systems vs high-pressure ridge dominates whether temperature stays cool through midday
May 17 close-of-day official temperature reading from UK Met Office London weather station determines final settlement; no rounding
Recent UK springs 2-3°C above normal; any cooler-than-forecast day would push odds toward YES but exact 12°C remains unlikely
How does this market resolve?
Market resolves YES if the official UK Met Office recorded highest temperature for London on May 17, 2026 is exactly 12°C. Any other value resolves NO.
Polymarket Trade is an independent third-party interface to the Polymarket CLOB prediction market exchange on Polygon — not affiliated with Polymarket, Inc. Prediction markets aggregate trader expectations into real-time probability estimates. Every market question resolves YES or NO based on a specific event outcome; traders buy shares of the side they believe will resolve positively. Prices range 0¢ (certain no) to 100¢ (certain yes) and naturally reflect the crowd-implied probability of YES. Polymarket Trade is non-custodial — your funds never leave your wallet. Open the full interactive page linked above to place orders, see order book depth, and execute a trade.
