Tokyo June 21 Low Temp: 21°C Sits at 36%

Tokyo’s overnight temperature forecast for June 21 is trading at 36% for a 21°C low. That probability has been sliding. The combined momentum signal, a 14% drop in the past hour stacked against a 4% decline over 24 hours, points to traders repositioning away from the 21°C outcome as new atmospheric data filters in. The market is pricing uncertainty, not science.

The market question asks: what will be the lowest temperature recorded in Tokyo on June 21, 2026? The 21°C outcome is priced at $0.36 (YES) against $0.64 (NO), implying a 36% chance. Resolution closes at 12:00 UTC+9 on June 21. Total volume sits at $7,457, with $5,715 traded in the last 24 hours. Liquidity is $22,769.

How the Tokyo Temperature Contract Works

YES pays out if official temperature records confirm the overnight low in Tokyo on June 21 reaches exactly 21°C. NO covers every other outcome, meaning any reading above or below 21°C resolves the contract against YES holders. Competing outcomes include 20°C, 22°C, 23°C, 19°C, 24°C, 18°C, 17°C, 16°C, 15°C or below, and 25°C or higher.

• 21°C (primary outcome): $0.36 YES / $0.64 NO, implied probability 36%
• 20°C: competing outcome priced on the same Polymarket interface
• 22°C: competing outcome with its own independent contract
• 23°C and above: progressively lower probability outcomes
• 19°C and below: outcomes that would activate if a cooler-than-expected system moves through

A NO resolution happens any time the recorded low lands on any outcome other than 21°C. Tokyo in mid-to-late June typically sees overnight lows ranging between 19°C and 24°C, so the spread of plausible outcomes is genuinely wide. The Japan Meteorological Agency publishes official temperature readings for Tokyo, and those records determine resolution. With 11 competing outcomes on the board, the probability of any single one resolving YES is mechanically capped.

Sponsored Partner

Momentum and Market Signals

The momentum composite here is distinctly bearish for 21°C. A 14% hourly drop paired with a 4% 24-hour decline and a trend score of 65.30 suggests active selling pressure, likely driven by short-range weather model updates narrowing the forecast cone. When NWP models shift their ensemble means, these small weather markets can reprice sharply and quickly.

Total volume of $7,457 is thin by any standard. The 24-hour volume of $5,715 represents most of that total, which means this market lit up in the past day, probably as resolution approaches. Liquidity at $22,769 is relatively deep compared to volume, but with this little total traded, a single informed bet can move the price dramatically. Here’s what the measurements are telling us: thin liquidity means the current 36% price reflects a small number of participants, not broad consensus.

• The 1-hour price change of -14% and 24-hour change of -4%, combined with a trend score of 65.30, signal active repositioning away from 21°C, most likely tied to updated forecast model runs.
• Total volume of $7,457 is below $1M, meaning price can move sharply on any new data or large single trade.
• Liquidity of $22,769 exceeds 24-hour volume, suggesting the order book is deeper than current participation warrants.
• Trader sentiment leans bearish on this outcome: 36% YES versus 64% NO reflects a market that sees 21°C as the most discussed but not the most likely single outcome.
• With resolution in less than 24 hours, overnight forecast revisions from the Japan Meteorological Agency or major NWP model runs could reprice this contract in either direction.

Lines Analysis: Tokyo’s June Overnight Low

The case supporting 21°C rests on Tokyo’s climatological baseline for late June. The city’s June overnight lows cluster in the 19°C to 23°C range during the rainy season, with 21°C sitting near the center of that distribution. A typical baiu (rainy season) pattern with cloud cover and residual daytime heat often lands overnight lows in exactly this range. The current 36% price reflects that 21°C is genuinely plausible but not dominant when spread across eleven competing outcomes.

What makes this contract hard to hold is the mechanical reality of 12 discrete outcomes. Even if 21°C is the single most likely result, its probability ceiling in a fair distribution across adjacent outcomes is naturally below 50%. A cooler airmass pushing in from the northwest, or a warmer humid night from a persistent low-pressure system, would shift the resolution to 20°C or 22°C respectively. The Japan Meteorological Agency’s 48-hour forecast for Tokyo is the clearest signal available right now.

• Japan Meteorological Agency forecast update for June 20 to 21: any shift toward a cooler or warmer overnight low would move capital out of 21°C into adjacent outcomes.
• Ensemble model agreement: high agreement on 21°C supports the current price; spread toward 20°C or 22°C would push this price lower.
• Rainfall timing: a rain band passing through Tokyo during the overnight hours typically moderates temperature toward the 19°C to 21°C range.
• Urban heat island effect: Tokyo’s urban core rarely dips below 19°C in mid-to-late June, which compresses the lower tail of outcomes.
• Resolution time at 12:00: the official low will be drawn from the overnight and early morning window, the period most sensitive to synoptic-scale changes.

Total volume of $7,457 is the honest summary of conviction here. The data doesn’t care about the politics, but it does care about model uncertainty. Right now, the market is treating 21°C as the modal outcome in a genuinely uncertain distribution. The momentum signal favors selling, and with less than 24 hours to resolution, that trend is unlikely to reverse unless a late forecast update strongly anchors the overnight low at exactly 21°C.

LINES VERDICT

UNCERTAIN HOLD

The 21°C outcome is mechanically constrained by 11 competing possibilities and real forecast uncertainty. Momentum is selling, not buying.

What the market says: At 36% implied probability with a sharp hourly decline, the market sees 21°C as plausible but not probable. With resolution on June 21, any overnight forecast revision will move this price before the window closes.

Key unknown: The Japan Meteorological Agency’s final 24-hour forecast for Tokyo’s overnight low on June 21 is the single most important data point. A model consensus shift of even one degree would reprice this contract and its adjacent outcomes significantly.