Tokyo Hit 35°C on July 20, Market Resolved at 100% | Lines.com

Tokyo recorded a daily high of 35 degrees Celsius on July 20, 2026, resolving the Polymarket temperature market in full. The 35°C outcome captured the top bracket of the prediction range, confirming what the final hours of trading had already priced with near-certainty. The Japan Meteorological Agency’s official station data sealed the result at market close on July 20 at 12:00 p.m. JST.

The market opened with an implied probability of just 26% for the 35°C outcome, meaning traders initially underpriced this result. By close, the probability had surged to 100%, reflecting a complete repricing over the final 48 hours of the market. Total volume reached $63,975, with $43,029 of that traded in the final 24 hours alone, a sign that conviction came late but arrived in force.

Tokyo Reached 35°C as Midsummer Heat Conditions Took Hold

The 35°C reading placed Tokyo at the threshold Japan’s meteorological services formally classify as a mōsho-bi, or intense heat day. July 20 falls at the end of the rainy season transition window, when cloud cover typically clears and solar radiation peaks in the Kanto plain. Urban heat island effects in central Tokyo compound ambient temperatures, consistently pushing official station readings above surrounding suburban areas. The combination of post-rainy-season sun exposure and Tokyo’s dense built environment made a reading at or above 35°C physically plausible throughout the market’s duration.

The market’s final probability reached 100% at close, meaning no residual uncertainty remained in the price. The sharp move from 26% at open to full resolution happened across two trading sessions, with a 57.5% net gain in the 24 hours before close. Traders who recognized the atmospheric setup early had a wide window to accumulate at discounted prices.

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How the Market Performed: Late Repricing, Correct Final Call

The 35°C market opened at an implied probability of 26%, a significant underpricing given Tokyo’s July climatology and the atmospheric signals visible by mid-month. The 74-percentage-point gap between the opening price and the confirmed outcome represents a substantial mispricing that persisted until late in the market’s life. The price did not begin its decisive move until July 18 and 19, gaining roughly 6.5% and then 8.5% on those consecutive days before the final 47% surge on July 19 brought the probability close to certainty.

Total volume of $63,975 across the market’s life is modest by major event standards, but the $262,909 liquidity figure suggests the order book was deep enough to support meaningful price discovery once directional conviction formed. The late concentration of volume, with $43,029 of total trades occurring in the final 24 hours, indicates that most participants waited for corroborating weather data before committing capital. That pattern is consistent with science-based markets where real-world observational data drives convergence rather than narrative or sentiment.

What This Means for Tokyo’s Heat Outlook and Climate Markets

A confirmed 35°C reading on July 20 aligns with the broader warming trend affecting Japan’s urban centers. Tokyo’s mean July maximum temperature has climbed roughly 3°C over the past century, with intense heat days becoming more frequent over the last two decades. A single-day temperature market captures a snapshot, but the pattern of late-market convergence here reflects a recurring dynamic in climate-adjacent prediction markets: traders underprice physically likely outcomes when early forecast uncertainty is high, then reprice rapidly as observational data confirms the direction.

The binary structure of this market worked well for resolution clarity. Temperature markets with multiple outcome brackets provide more granular signal than a simple yes-or-no format, and the 35°C bucket resolved cleanly against official station data. For future Tokyo summer temperature markets, the late-July window between July 18 and July 25 represents peak probability territory for readings at or above 35°C, based on historical JMA station records for the Kanto region.

• Tokyo’s intense heat day frequency has increased across the last two decades, making 35°C readings in late July a climatologically expected event rather than an outlier.
• The rainy season typically ends around July 20 in the Kanto region, removing cloud cover and driving a sharp rise in daily maximum temperatures precisely at this market’s resolution window.
• Traders relying on forecast data rather than climatological base rates systematically underpriced this outcome from open, creating an extended window of value on the 35°C bracket.
• Future temperature bracket markets in Tokyo would benefit from market structures that open closer to the target date, when numerical weather prediction models have higher confidence at shorter forecast horizons.

LINES RESOLUTION VERDICT

UNDERPRICED YES: LATE BUT ACCURATE

The 35°C outcome was physically consistent with Tokyo’s late-July climatology from the start, and the market’s failure to price that until the final 48 hours reveals a persistent gap between climate base rates and trader intuition in temperature markets.

What the market showed: The 35°C outcome opened at a 26% implied probability and closed at 100%. Traders underpriced a climatologically plausible result for most of the market’s life, then converged correctly as observational data reduced forecast uncertainty in the final two sessions.

This analysis reflects the confirmed resolution of this market as of July 20, 2026. Prediction market probabilities reflect collective trader conviction, not guaranteed outcomes. Lines.com does not accept bets or provide financial or gambling advice.