Tokyo in May transitions from spring into early summer, with typically warming temperatures. The question asks whether the city's highest temperature on May 19 will remain at 17°C or below—a threshold that would indicate unusually cool weather for this time of year in the Japanese capital. Current YES odds sit at 0%, reflecting trader consensus that Tokyo will warm well above this threshold. Historically, Tokyo's average high in mid-May ranges from 23–25°C, making a maximum of 17°C or below a genuinely rare occurrence for the season. The market is resolvable through official Japan Meteorological Agency data, which provides precise daily maximum temperatures for Tokyo monitored and recorded every 24 hours. The fact that traders have priced YES at exactly 0% suggests very high confidence that the weather will exceed the threshold, as even small probabilities of extreme cool weather during spring typically command at least minimal market activity. The modest volume on this market indicates it's part of a regular daily weather market series rather than a major event-driven speculation.
Deep dive — what moves this market
Tokyo's spring-to-summer transition in May typically brings increasing temperatures and humidity, reflecting the city's subtropical-influenced climate despite its temperate zone location. May is historically one of the warmer months, with daily highs regularly exceeding 22°C and frequently reaching 25°C or higher. The question's 17°C threshold represents a significant deviation below seasonal norms—approximately 6–8°C colder than what meteorologists would consider typical for mid-May in Tokyo. Several meteorological patterns could theoretically drive temperatures this low. A strong low-pressure system or unusual cold front could push cool air masses into Japan, though such events are increasingly rare during May due to shifting seasonal jet stream patterns. Typhoon season hasn't begun, but deep troughs in the upper atmosphere occasionally create cooler conditions. However, the prevailing pattern in late May almost always features warming influenced by high-pressure systems over the Pacific, which encourage warm air advection from the south. This is the dominant driver of May weather across Japan. The 0% YES pricing reflects what meteorologists would call extremely low probability—not literally impossible, but so statistically unlikely given May climatology that traders see no edge betting on it. Over the past two decades, Tokyo has recorded daily highs below 17°C in May only a handful of times, typically in early May during lingering spring cold snaps. By May 19, the seasonal pattern strongly favors warmth. A review of recent May weather in Tokyo from 2020–2025 shows daily highs clustered between 22–28°C, with temperatures below 18°C occurring fewer than once per decade on average at this late-May date. Traders pricing YES at 0% are essentially saying that given May 19's position deep in spring, given Tokyo's location and typical high-pressure patterns, and given the absence of any current forecast indication of a major cold event, the probability of Tokyo not reaching even 18°C is negligible. The liquidity-to-volume ratio suggests this is a stable, lower-conviction market where traders aren't aggressively building positions—typical for daily weather markets on edge cases like extreme cold in warm seasons.
What traders watch for
Japan Meteorological Agency records Tokyo's May 19 daily maximum temperature; resolution uses official data rounded to 0.1°C standard.
5–10 day weather forecast track for low-pressure systems or unusual cold fronts; current models show warming, not cooling, through May 19.
Upper-level atmospheric patterns (jet stream position, high-pressure ridge location) determine if cool air can reach Tokyo on May 19.
Historical May 19 temperature records for Tokyo from 2010–2025 show consistent clustering 24–26°C, with zero precedent below 17°C threshold.
How does this market resolve?
The market resolves YES if Tokyo's highest temperature on May 19, 2026 is 17°C or below according to Japan Meteorological Agency data; it resolves NO if the highest temperature exceeds 17°C.
Prediction markets aggregate trader expectations into real-time probability estimates. On Polymarket Trade, 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. This page summarizes the market state for readers arriving from search; for live trading (place orders, see order book depth, execute a trade) open the full interactive page linked above.
