Highest temperature in Tokyo on August 4?

Platform comparison

Market context

Tokyo’s hottest reading on 4 August 2026 will be set from the maximum temperature recorded at Haneda Airport, not from a city-wide average, so short-lived afternoon heat spikes matter more than the morning outlook. Current public forecasts cluster the day’s high in the mid-to-upper 20s Celsius, with the Japan Meteorological Agency showing Tokyo at 28°C/21°C and a 40% rain chance, while other services sit a little higher around 85–88°F (about 29–31°C), which is consistent with a late-summer Tokyo baseline rather than an extreme-heat setup.[11][2][6]

That framing helps explain the 0% crowd-implied YES price: a 0% quote on a temperature-band market usually means the market thinks the target range is effectively unreachable, not that the outcome is impossible. For comparison, JMA’s normal August maximum for Tokyo is 28.5°C, and Tokyo’s August forecasts across several providers typically sit close to the seasonal average, which is why traders on Polymarket often read these as low-volatility weather contracts, whereas Kalshi, Betfair and Smarkets price the same underlying with decimal odds and different deductions for fees or commission. KYC reach also differs: Kalshi is US-focused, Betfair and Smarkets are more jurisdiction-dependent, while Polymarket access and market mechanics have historically been broader but less uniform by region.

The main catalysts are the day’s actual temperature curve at Haneda, cloud cover, showers and any late-afternoon clearing that could allow a brief peak before the settlement window closes at 12:00 UTC. Tokyo forecasts currently show mixed cloud and scattered shower risk, with hourly services indicating temperatures already in the mid-20s Celsius before dawn and a possible climb towards the high 20s or low 30s later in the day if rain stays patchy.[1][11][12] Traders should watch the latest JMA updates and high-resolution hourly forecasts rather than monthly averages, because a one- or two-degree miss can move the market between adjacent settlement bands.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in Tokyo on August 4? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Robinhood Prediction Markets, which mirrors the Polymarket order book at 0% fees.

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

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.

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.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Robinhood Prediction Markets offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.