Highest temperature in Chengdu on July 31?

Platform comparison

Market context

At Chengdu Shuangliu International Airport, the relevant figure is the *day’s peak temperature* on 31 July, taken from the station’s Wunderground history page rather than a citywide average, so programmatic watchers should key off the single highest hourly observation in Celsius and ignore forecast-style summaries unless they are being used only as priors. The market is therefore about whether the airport’s maximum clears the next integer threshold in the chosen range, which makes the final hours of the local day the only period that can still change the outcome once the peak is logged.

For context, late-July Chengdu is usually hot but not extreme: normal daytime highs are commonly in the low-to-mid 30s Celsius, with several forecasters showing around 33-35°C for 31 July and some suggesting brief spikes to 37°C or higher. [3][8][12][15] That range matters because a 0% crowd price usually means the market is treating the relevant band as effectively impossible from the available signals, yet the historical climatology and current model spread still point to materially warmer conditions than that. July is also one of Chengdu’s wetter months, with humid air and frequent rain, so cloud cover or thunderstorms can cap the top temperature even when the broader heat profile is strong. [6][13][15]

A trader monitoring this mechanically would watch the hourly forecast and any nowcasts that update as the afternoon develops, plus any rain or thunder alerts that could suppress the max temperature before it is recorded at the airport. AccuWeather’s hourly forecast for Chengdu has shown mid-30s Celsius readings through the afternoon, while Meteobox and Ventusky both indicate afternoon highs around 35-37°C, which is the kind of spread that can move a programmatic model between adjacent settlement bands. [12][14][9] The useful dependency chain is simple: forecast update, observed airport temperature, then Wunderground’s daily maximum for the station.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi 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 itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.