Shanghai's weather in mid-May transitions between late spring and early summer. The 0% odds reflect the meteorological improbability of a maximum high of exactly 18°C on May 19. Shanghai's average high in May ranges from 22°C to 28°C, making 18°C substantially below the normal May range. For this outcome to occur, the region would need unseasonably cool air, possibly from a cold front penetrating southern China. The market resolution is straightforward—historical weather data from Shanghai's official meteorological bureau will determine the maximum temperature for May 19. The extreme condensation of odds to 0% suggests traders have already assessed the probability as vanishingly small. This weather-specific market is resolvable with complete certainty using official records, unlike prediction markets tied to human judgment or policy decisions. The $6,511 in liquidity and $530 daily volume indicate this is an active trading venue, though the overwhelming trader consensus toward NO suggests any YES position would require extraordinary confidence in an unusually cool day in Shanghai.
What factors could move this market?
Shanghai's climate during May represents a transitional zone between the temperate spring and the humid subtropical summer that typically dominates by June. The city's topography—situated on the Yangtze River Delta with extensive water systems—moderates extreme swings in temperature. Historically, May highs in Shanghai rarely fall below 20°C, with the 100-year May average clustering around 24-25°C for the daily maximum. An 18°C high would represent weather roughly two to three standard deviations below the May mean, a frequency that meteorologists might expect perhaps once or twice in a human lifetime in this region. For such a cool day to materialize on May 19 specifically, Shanghai would need to experience an intrusion of cold Arctic air or the remnants of a strong polar vortex displacement, scenarios that become increasingly rare as the Northern Hemisphere progresses into late spring. Historical records show that Shanghai does occasionally see unusually cool May days—often associated with strong weather systems from Siberia or disruptions in the East Asian jet stream. However, the timing would need to align perfectly: a cold front arriving just as May 19 begins, with insufficient solar heating to warm the air mass above the current threshold. The 0% market odds imply that traders, having evaluated both historical precedent and 10-day weather forecasts, have effectively zeroed out this possibility. This extreme probability compression likely reflects a combination of factors: the recency of weather models showing no such pattern developing, the statistical rarity of such an outcome, and perhaps a reflexive skepticism from traders familiar with Shanghai's typical May conditions. To push YES, Shanghai would need a rare convergence: a major Arctic outbreak penetrating to 30°N latitude, timing its peak on exactly May 19, and overcoming the seasonal warming trend inherent to late spring. Factors pushing NO include seasonal solar intensity, typical trade wind patterns that bring warmer Pacific air, and the absence of any large-scale atmospheric disruption in current forecast models. The lack of volume toward YES suggests no serious contrarian traders currently disagree. This type of binary weather market has clear resolution criteria—the Shanghai meteorological administration publishes daily temperature data that is independently verifiable and not subject to interpretation. The extreme odds divergence between YES and NO reflects genuine consensus among participants that 18°C on May 19 falls far outside the distribution of plausible outcomes for Shanghai in mid-May. Such definitive odds compression is rare in prediction markets and indicates near-universal trader confidence in a NO resolution.
What are traders watching for?
May 19 maximum temperature data release from Shanghai Meteorological Bureau determines final market resolution and trader payouts.
10-day weather forecast models through May 18 critical; any emerging Arctic outbreak signal could shift trader expectations.
Seasonal warming trend accelerates into late May; cold air masses become increasingly rare and shorter-lived.
Shanghai's historical May temperature records show no instance of a daily high at 18°C in modern meteorological archives.
How does this market resolve?
Market resolves on May 19 using official Shanghai Meteorological Bureau data. YES wins if the maximum daily temperature equals exactly 18°C; any other reading triggers NO payout.
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.
