Tokyo Hit 21°C Low on July 3 | Lines.com

Tokyo recorded a minimum temperature of 21°C on July 3, 2026, confirming the outcome that Polymarket traders had priced at near-certainty. The measurement settled a multi-outcome market covering the full range of possible overnight lows, from 16°C or below to 26°C or higher. Traders assigned the 21°C bucket a 98.6% probability, and the reading matched that conviction precisely.

The implied probability on this market sat at 98.6% at article time, with a yes price of 0.99. The final price at close matched that figure. A total of $30,201 in volume moved through the market, with $20,962 of that arriving in the 24 hours surrounding resolution. That late-surge concentration tells a clear story: the measurement data was becoming visible, and traders positioned accordingly.

Tokyo’s July 3 Low Confirmed at 21°C

Japan’s Meteorological Agency tracks hourly surface temperatures across Tokyo’s observation network. The July 3 minimum of 21°C falls within the city’s typical early-July range, when the rainy season transition often keeps overnight lows elevated but not extreme. A reading of 21°C sits at the cooler end of what Tokyo normally sees in early July, consistent with residual cloud cover or a brief atmospheric trough suppressing the usual humid heat.

The market structure spread probability across 11 discrete temperature buckets. The 21°C outcome absorbed nearly all trader conviction, leaving the adjacent buckets at minimal prices. In the final hours before resolution, the yes price on 21°C climbed from roughly 0.40 at open to 0.99 at close, a move of nearly 60 percentage points that reflected real-time weather data feeding into trader positioning rather than speculative momentum.

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How the Market Performed on Tokyo’s July 3 Low

The market opened the 21°C outcome at 0.40, meaning traders initially saw roughly even odds across several temperature buckets. Here’s what the measurements are telling us: the 98.6% close price reflected high-confidence alignment with observed data, not a structural repricing of uncertainty. The 24-hour price change of +22.6% was the market digesting an incoming temperature reading, not traders speculating on meteorological models.

The market is pricing uncertainty, not science, and that gap was large early. A 0.40 opening price on what became the correct outcome suggests genuine ambiguity across the temperature range during the pre-resolution window. The $144,120 in liquidity available at resolution ensured the late-stage price discovery was orderly. Total volume of $30,201 is modest for a resolved science market, reflecting the narrow, hyper-specific nature of a single-day urban temperature reading.

What a Single-Day Tokyo Low Tells Us Going Forward

A confirmed minimum of 21°C on July 3 adds a single data point to Tokyo’s growing record of early-summer overnight temperatures. Japan’s Meteorological Agency and urban heat researchers use these granular readings to track the progression of the rainy season and the onset of the city’s intense summer heat. Tokyo’s overnight lows have trended upward over the past three decades, driven by urban heat island intensification and broader regional warming patterns. A 21°C minimum in early July is not alarming, but it is part of a longer signal worth watching.

The binary-style structure of this multi-outcome market worked reasonably well for a discrete measurement question. The data doesn’t care about the politics, and temperature markets of this type reflect that cleanly: once actual station data becomes accessible, prices converge fast. The question is whether this market format is the right tool for capturing genuine meteorological uncertainty or whether it primarily rewards access to near-real-time weather feeds over predictive skill.

• Japan’s Meteorological Agency publishes hourly surface temperature data for Tokyo, which feeds directly into late-stage Polymarket price discovery on temperature outcome markets.
• Tokyo’s early-July overnight lows have averaged between 22°C and 24°C over the past decade, making a 21°C reading slightly cooler than the recent norm and consistent with a transitional atmospheric pattern.
• The 24h volume of $20,962 represented 69% of total market volume, confirming that most trading activity concentrated in the final window when observational data was available.
• Future markets covering Tokyo daily temperature extremes would benefit from tighter bucket intervals, particularly around the 20-24°C range where early-July readings cluster most densely.

LINES RESOLUTION VERDICT

YES: CORRECTLY PRICED AT RESOLUTION

Traders priced the 21°C outcome with precision by close, but the 0.40 opening price reveals that the early market was genuinely uncertain, and real accuracy only arrived with the data itself.

What the market showed: The implied probability opened at roughly 40% and closed at 98.6%. The confirmed outcome was 21°C. Traders who moved late captured the signal; early positioning reflected legitimate uncertainty across Tokyo’s July temperature distribution.