Seoul Low Temperature June 4: Will 18C Hit?

Seoul’s overnight low on June 4 is one of the tighter meteorological calls on Polymarket right now. The 18°C outcome carries a 37.5% implied probability, making it the single most-traded outcome in a market split across eleven temperature bins. That 13.5% price surge in the last 24 hours tells you something shifted in the atmospheric data. Here’s what the measurements are telling us.

The market question asks: what will Seoul’s lowest temperature be on June 4? The 18°C outcome is priced at 0.38, with the field (every other outcome) sitting at 0.63. The market closes June 4 at 12:00 PM UTC. Total volume stands at $7,074, with $5,658 of that traded in the last 24 hours.

How the Seoul Temperature Contract Works

This market resolves to whichever temperature bin matches Seoul’s verified minimum on June 4. The Korea Meteorological Administration publishes official daily low readings for Seoul Station, which serves as the standard reference point. If the actual low hits 18°C exactly, the 18°C contract pays out. Any other reading sends money to a different bin.

• 18°C outcome: priced at 0.38, implying 37.5% probability.
• All other outcomes combined: priced collectively above 0.62, covering 19°C, 17°C, 16°C, 15°C, 14°C or below, 20°C, 21°C, 22°C, 23°C, and 24°C or higher.

The case against 18°C landing: Seoul’s early June lows are genuinely variable. A stronger southwesterly flow pushing warmer air into the Korean Peninsula overnight could push the low to 20°C or above. Alternatively, a retreating front or clear-sky radiative cooling could drop the reading to 16°C or 17°C. The Korea Meteorological Administration’s short-range guidance through June 4 will be the decisive input, and that guidance can shift meaningfully within 12 hours of the observation window.

Momentum and Market Signals

The momentum composite here is notable. Price moved up 13.5% in 24 hours with a trend score of 52.21, suggesting moderate directional conviction rather than a blowout surge. The most likely driver is updated numerical weather prediction model output, specifically the KMA’s own short-range ensemble and the European Centre’s deterministic run, both of which are updated twice daily. When those models converge on a narrow overnight temperature range centered near 18°C, traders respond.

Total volume at $7,074 is thin. The 24-hour volume of $5,658 represents roughly 80% of all money ever traded in this contract, which signals a very recent spike in interest rather than sustained engagement. Liquidity sits at $16,319, which is healthy relative to volume, but the low absolute volume means a single moderate-sized order could move the 18°C price by several percentage points. The market is pricing uncertainty, not science, and thin books amplify that.

• The 13.5% 24-hour price gain on the 18°C outcome reflects fresh model alignment, not a fundamental shift in Seoul’s climate baseline.
• Volume below $10,000 total means confidence level here is LOW. Price can reprice sharply on a single weather update or a new KMA bulletin.
• The 1-hour change of 0.0% suggests the initial model-driven move has paused. Traders are waiting for the next model run before adding size.
• Liquidity at $16,319 is adequate to absorb small trades without major slippage, but large bets would move price meaningfully.
• The bearish lean (62.5% NO) reflects the market’s collective judgment that 18°C is the modal outcome but not a near-certainty, given the width of the temperature distribution across eleven bins.

Lines Analysis: What the Seoul Data Favors

Seoul in early June sits in a transitional atmospheric pattern. The East Asian monsoon front, known locally as jangma, typically does not establish itself over the Seoul metropolitan area until mid-to-late June. Before that, overnight lows in the 17°C to 20°C range are climatologically common. The Korea Meteorological Administration’s historical station data for Seoul in the first week of June shows modal daily minimums clustering in exactly that band. An 18°C low is not a tail event. It sits near the center of the June 4 temperature distribution, which explains why it holds the highest single-outcome probability even at 37.5%.

What makes the other bins real: Seoul’s overnight temperatures respond quickly to synoptic changes. A clear night with low humidity and weak winds favors radiative cooling that can push lows to 15°C or 16°C. A cloudy, humid night with southerly flow can keep lows at 21°C or above. The Korea Meteorological Administration’s ensemble spread for June 3 to 4 likely shows meaningful variance across that range, which is why no single outcome dominates above 40%. The data doesn’t care about the politics of which bin traders prefer.

• Korea Meteorological Administration: if the agency’s 24-hour forecast narrows to a range centered on 18°C to 19°C, the 18°C bin should see further buying.
• European Centre for Medium-Range Weather Forecasts model update: if the 00Z or 12Z run on June 3 to 4 shifts the Seoul surface temperature toward 20°C or above, expect capital to migrate to the higher bins.
• Synoptic pattern: a clear-sky radiative cooling scenario overnight June 3 to 4 would push probability toward 16°C or 17°C outcomes.
• KMA official forecast bulletin: any update citing fog, low cloud, or a stalled front near Seoul would reduce radiative cooling risk and support the 18°C to 20°C range.

Total volume of $7,074 is too thin to treat as a strong wisdom-of-crowds signal. The 24-hour volume spike suggests informed traders acted on specific model data, but the market has not been tested by large opposing capital. The data currently favors the 18°C bin as the modal outcome, but the distribution is genuinely wide, and the adjacent bins at 17°C and 19°C are meaningful competitors.

LINES VERDICT

MODAL OUTCOME, NOT A LOCK

The 18°C bin holds the highest single-outcome probability in a genuinely wide temperature distribution. Model alignment drove the recent price move, but thin volume limits confidence in that signal.

What the market says: 37.5% implied probability means traders see 18°C as the most likely single outcome while assigning a 62.5% chance to everything else. With the market closing June 4 at noon UTC, overnight model runs and the KMA’s morning forecast update are the last meaningful inputs before resolution.

Key unknown: The Korea Meteorological Administration’s final short-range ensemble output for the Seoul June 4 overnight period is the single data point that would reprice every bin in this contract. If that output narrows or shifts, expect rapid movement across all outcomes.

Scientific Context: Seoul June Low Temperatures

Seoul’s climatological daily minimum for the first week of June, based on Korea Meteorological Administration station data, sits in the 16°C to 20°C range. The 18°C outcome aligns with the historical center of that distribution, which is why it commands the highest single-outcome probability. The pre-monsoon pattern in early June produces variable overnight temperatures depending on cloud cover, wind direction, and the position of the subtropical high. Events that would reprice this market before June 4 resolution include a KMA forecast update shifting the overnight low range by 2°C or more in either direction, or a significant change in the synoptic pattern over the Korean Peninsula driven by a faster-than-expected monsoon advance.

Will Seoul’s June four low hit eighteen degrees Celsius?

The 18°C outcome holds a 37.5% implied probability, the highest of any single bin in an eleven-outcome market. That reflects its position near the center of Seoul’s early June low temperature distribution.

What pays out if the low is seventeen or nineteen degrees?

Those alternative bins each carry their own separate probability and price. A 17°C or 19°C reading would pay holders of those specific contracts, not the 18°C outcome.

What data would move the 18°C price most sharply?

A Korea Meteorological Administration forecast update or a major numerical weather model run shifting the June 4 overnight low range by two degrees or more in either direction would reprice all bins rapidly.

When does this market resolve?

The market resolves June 4, 2026 at 12:00 PM UTC, using the official Seoul minimum temperature as reported by the resolution source.

Is this market reliable given the low volume?

Total volume is $7,074, which is below $10,000. Thin liquidity means a single moderate trade can move prices meaningfully. Treat current probabilities as directional signals, not precise measurements.