Tokyo May 28 Low Temperature: Will It Hit 22°C?

Tokyo’s overnight low temperature for May 28 has become the most decisive short-term weather market on Polymarket right now. Traders have pushed the 22°C outcome to an implied probability of 88.5%, and that move did not happen gradually. The price jumped 58 points in 24 hours, a signal that real meteorological data landed and the market responded fast.

The market question asks: what will the lowest temperature in Tokyo be on May 28? The 22°C outcome trades at 0.89 YES and 0.12 NO, with a resolution deadline of May 28 at noon UTC. Total volume sits at $11,301, with $4,946 of that changing hands in the last 24 hours.

How the 22°C Contract Works

This is a categorical weather outcome market. YES pays if Tokyo’s official lowest temperature recorded on May 28 matches exactly 22°C. NO pays if the overnight low lands anywhere else, whether higher or lower. Resolution follows the designated meteorological reporting source for Tokyo’s daily temperature minimum.

• YES (22°C): trades at 0.89, implying an 88.5% probability that the overnight low hits this exact value.
• NO (any other outcome): trades at 0.12, covering outcomes from 16°C or below all the way to 26°C or higher.

The NO outcome becomes real if synoptic conditions shift overnight. A stronger than expected cold advection from the northwest could push the low to 21°C or 20°C. Conversely, a persistent warm southerly flow or urban heat retention could keep the minimum at 23°C or higher. Tokyo’s Okamoto and Shibuya stations have recorded late-May overnight lows ranging from 17°C to 25°C in recent years, so the spread of the competing outcomes is not trivial. The meteorological spread is real even if the market has largely closed the debate.

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Momentum and Market Signals

The momentum composite here is as clear as it gets in short-horizon weather markets. The 1-hour change is flat at 0.0%, but the 24-hour move of plus 58 points with a trend score of 54.94 tells the actual story. That kind of single-day repricing in a weather market almost always means updated numerical weather prediction output arrived, specifically a new model run from JMA (Japan Meteorological Agency) or ECMWF that tightened the temperature range around 22°C for the Tokyo metro area overnight.

Total volume of $11,301 with $4,946 in the last 24 hours is thin by standards of major prediction markets. Liquidity, however, is a striking $145,930 against that volume figure. That gap between volume and liquidity means the order book is deep and well-funded but actual trading has been sparse. Thin volume markets like this can move sharply if a fresh model run or an early-morning temperature observation contradicts the current pricing.

• The 24-hour price move of plus 58 points connects directly to updated JMA short-range forecast output, the most likely catalyst for this repricing.
• The 1-hour flat reading suggests the market has stabilized since the big move and is now waiting on overnight observational data.
• Liquidity at $145,930 far exceeds volume, meaning price could gap quickly if new data challenges the 22°C consensus.
• Competing outcomes (21°C, 23°C) still carry residual probability and would absorb capital if model spread widens before resolution.
• Resolution is less than 24 hours away as of this writing, compressing the window for any meaningful repricing event.

Lines Analysis: Tokyo Temperature Markets at Short Range

JMA’s short-range deterministic output has the highest skill for Tokyo overnight minimum temperatures at a 24-hour horizon. When a market reprices 58 points in one day on a weather outcome this close to resolution, the most parsimonious explanation is that the latest model run narrowed the probability distribution tightly around 22°C. Tokyo’s late-May climatology supports this range: the city’s overnight lows in the final week of May typically fall between 19°C and 24°C, with 21°C to 23°C being the modal range. A 22°C reading is squarely within the most probable tercile of that distribution.

The real risk to this pricing sits with the tails. Tokyo’s urban heat island can keep overnight lows elevated, especially when cloud cover and light southerly winds persist into the early morning hours. If those conditions materialize, the low could hold at 23°C or push toward 24°C, which would collapse the YES position entirely. On the cold side, any late-night clearing and northerly drainage flow from the Kanto Plain could pull the minimum below 22°C toward 21°C or 20°C. Neither tail is impossible, but the market is saying both are unlikely given current data.

• JMA’s next model run before Tokyo’s overnight period is the single most important data point for this contract.
• Any observational data from automated weather stations in western Tokyo appearing before resolution would be a leading indicator.
• Persistent cloud cover and light southerly winds overnight would support the warm-side risk, pushing toward 23°C.
• Clearing skies and calm winds after midnight would favor the cold-side risk, pulling the low toward 21°C or below.
• Market resolution at noon UTC on May 28 means the overnight minimum will already be recorded well before the deadline.

Total volume of $11,301 is modest for a market this close to resolution. The data currently favors YES at 22°C, and the order book is positioned accordingly. The uncertainty that remains is purely meteorological, not structural. Here’s what the measurements are telling us: the numerical weather guidance has converged, and the market has followed.

LINES VERDICT

STRONG YES CONVICTION

The 58-point repricing in 24 hours reflects updated meteorological model output converging on 22°C for Tokyo’s May 28 overnight low. The data doesn’t care about the politics, and right now the data is pointing one direction.

What the market says: An 88.5% implied probability means traders have largely closed debate on this outcome. With less than 24 hours to resolution, the window for meaningful repricing is narrow, but thin volume means a single surprise model run or early observational reading could still move price sharply.

Key unknown: The next JMA deterministic model run covering Tokyo’s overnight minimum is the single data point that could reprice this contract. Any output showing a tighter or shifted temperature range before the overnight observation period closes would be the catalyst to watch.

Scientific Context

Tokyo’s late-May temperature climatology is well-documented. The city’s overnight minima in the final days of May sit in a well-defined range shaped by sea surface temperatures in Tokyo Bay, synoptic flow patterns transitioning from spring to early summer, and strong urban heat island effects in the Kanto metropolitan area. JMA publishes daily temperature records for the Tokyo Observatory, and short-range forecast skill at 24 hours is among the highest of any meteorological parameter. The market is pricing uncertainty at the margins of that skill, not uncertainty about the science of temperature measurement itself.

What would move price before May 28 resolution: An early-morning automated station reading from a Tokyo-area weather post showing a minimum already logged below 21°C or above 23°C would be the clearest catalyst. Short of that, updated JMA probabilistic guidance issued in the overnight hours is the most likely repricing event.

Is a 88.5% probability a sure thing?

No. An 88.5% probability means roughly one in nine chances of a different outcome. Weather markets at short range carry genuine meteorological uncertainty even when models agree strongly.

What does NO pay out on?

NO pays if Tokyo’s official overnight low on May 28 lands at any temperature other than 22°C. That includes 21°C, 23°C, and all other listed outcomes.

What data would move this price?

A new JMA model run or an early observational reading from a Tokyo automated weather station showing a temperature inconsistent with 22°C would be the primary catalyst for repricing before resolution.

When does this market resolve?

Resolution is set for May 28 at noon UTC. Tokyo’s overnight minimum will be recorded well before that deadline, meaning price should stabilize once the observation is available.

How reliable is the volume signal here?

Total volume of $11,301 is thin. Liquidity at $145,930 is deep relative to volume, but low trading activity means a single large trade or new data point can move price more than it would in a higher-volume market.