Highest temperature in Seoul on July 20?

Platform comparison

Market context

Seoul will record its peak daytime temperature on 20 July 2026 at the Incheon International Airport Station, the official meteorological reference for the city. Historical data confirms July is South Korea’s hottest and most humid month, with daytime highs typically spanning 25–30°C and occasional spikes nudging above 30°C during the tail end of the Jangma rainy season [1][3]. The crowd-implied 0% probability for any specific range suggests traders are either pricing in a near-certain outcome outside the offered brackets or facing a liquidity gap where no meaningful odds exist, a divergence from Kalshi’s US-only, KYC-mandated model and Betfair’s 2–5% commission structure that often sustains tighter spreads on weather events [2].

Comparable July records in Seoul show average midday temperatures anchoring near 27°C, with cooler, rainy spells briefly dropping highs to 18°C, yet sustained heatwaves regularly pushing peaks into the upper 20s or low 30s [3]. Traders should monitor the official Wunderground daily history for RKSI, the sole resolution source, and watch for any late-July extensions of the Jangma season that could suppress temperatures below typical summer anchors [1]. Unlike Polymarket’s 0% on-chain USDC settlement and no-KYC access up to $1,500, platforms like Kalshi require full identity verification and charge up to 7% per trade, while Smarkets and Betfair impose commission fees that erode returns on thin-margin weather markets [2].

Sources: 1 · 2 · 3

Methodology

We read Highest temperature in Seoul on July 20? 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 mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). On-chain settlement clears in minutes — the fastest payout path of the four.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.