Singapore sits just 1.3 degrees north of the equator with a tropical maritime climate characterized by warm, humid conditions year-round. The highest daily temperatures typically range from 30°C to 35°C throughout the year, making a daily high of exactly 27°C exceptionally cool for the island and well below historical norms. May falls during the southwest monsoon season, when afternoon thunderstorms are common and consistent moisture keeps temperatures warm despite increased cloud cover and humidity. For Singapore's daily high to reach only 27°C would require either highly unusual weather patterns—such as an extended cloudy period with persistent rain, strong winds, and unusual air masses—or potentially remnants of a tropical system bringing significantly cooler air from the north. Such rare cooling events occur perhaps once or twice annually when severe weather systems arrive. The extremely low 1% YES odds reflect trader conviction that this outcome represents a statistical anomaly, highly improbable given decades of historical temperature data and established seasonal patterns. The market resolves based on the highest temperature recorded at Singapore's official Meteorological Service weather station on May 3, 2026.
Deep dive — what moves this market
Singapore sits just 1.3 degrees north of the equator, giving it one of the most consistent tropical climates on Earth. The city-state experiences two monsoon seasons: the southwest monsoon (May to September) and the northeast monsoon (December to March), with inter-monsoon periods in between. Throughout the year, average daily highs typically range from 31°C to 33°C, with absolute minimum daily highs rarely dropping below 29°C even during the wettest, cloudiest periods. Historical data from the Meteorological Service Singapore shows that days with a high of 27°C or lower occur perhaps once or twice per year at most, usually during the heaviest rainfall events or when tropical systems bring anomalous atmospheric conditions.
For the market to resolve YES, Singapore would need to experience extraordinary weather on May 3. A tropical cyclone or deep low-pressure system tracking nearby could bring sustained cloud cover, heavy rain, and strong winds that suppress maximum temperatures. Alternatively, a rare prolonged weather system or unusual upper-level dynamics could cool the airmass. Historical precedent suggests this is possible but uncommon—severe tropical storms do occasionally impact Singapore, though direct hits are infrequent.
Conversely, the vastly more probable outcome is a typical May day: afternoon highs around 32-34°C despite monsoon-season cloud cover and showers. Even on rainy monsoon days, the retained heat and humidity typically drive afternoon temperatures well above 30°C. The thermal inertia of the tropical ocean and the strength of the May sun make sub-30°C daily highs exceptionally rare. Singapore's geography—a small, densely urbanized island with the sea on all sides—means even heavy cloud and rain rarely suppress the high enough to reach 27°C.
The current 1% YES odds reflect a rational assessment: a 27°C high is a multiple-standard-deviation event from historical norms. Traders are implicitly pricing in the minuscule probability of a severe tropical weather system, volcanic aerosol loading, or other major atmospheric disruption. The 1% level suggests the market is pricing perhaps a 1-in-100 scenario, consistent with historical frequency of such cool days. Traders monitoring this market will be watching tropical cyclone forecasts, upper-level atmospheric patterns, and any unusual meteorological alerts from Singapore's weather service in the days before May 3.
