Highest temperature in Seoul on May 31?

Platform comparison

Active sub-markets

Market context

Seoul's weather on 31 May 2026 will be measured at Incheon International Airport, where the highest temperature recorded across the entire day determines the settlement outcome. Late May in Seoul typically falls within late spring conditions, with daily highs ranging between 24–28°C, though heat waves can push readings several degrees higher. The 0% crowd probability suggests either extreme confidence in a specific temperature band or minimal trading activity on this particular market.

Historical May temperature records at Incheon show variability worth examining. The airport station has recorded May highs exceeding 30°C in roughly one-third of years over the past two decades, with 2018 and 2020 both reaching 31–32°C during late-May warm spells. This historical distribution means the current 0% probability on certain ranges likely reflects either a narrow consensus around 25–28°C or insufficient liquidity to establish meaningful odds. Kalshi and Betfair typically display decimal odds that make such extreme probabilities more visible than Polymarket's percentage format, potentially explaining why alternative platforms might show non-zero positions here.

Traders monitoring this market should track South Korean meteorological forecasts released in late May, particularly the Korea Meteorological Administration's 10-day outlook issued around 21 May. Pacific high-pressure systems and potential tropical moisture from early typhoon season activity represent the primary catalysts for above-average temperatures. Unlike Polymarket's flat fee structure, Betfair's commission-based model rewards accurate long-tail predictions, creating different incentive structures across platforms for niche weather markets with sparse initial liquidity.

Methodology

We read Highest temperature in Seoul on May 31? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live quote comes directly from the Polygon order book; the other three are listed with their platform attributes — fees, KYC, settlement currency, payment options — because a 1:1 contract comparison without API access would be guesswork.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Alternative, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket Alternative is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What does it cost to trade on Polymarket Alternative?

Zero. Polymarket Alternative routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket Alternative triggers a quick verification flow that finishes in minutes.