Highest temperature in Shanghai on June 20?

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Market context

The key change over the past 24–48 hours is that Shanghai has moved into late-June conditions where heat, humidity and rainfall can all swing the day’s maximum temperature, but the market is still being resolved on a single station reading at Pudong airport. June in Shanghai is typically hot and damp: averages for the airport sit around 27°C for daily highs, with sunny days often reaching 30–35°C, while rainfall becomes more frequent through the month.[1][2]

The 0% crowd-implied probability fits the seasonal setup rather than a claim that the event cannot happen. Late June can still produce sharp spikes; Shanghai has seen daytime highs near 38°C in late June in recent years, even though the broader June norm is much lower.[3] For this market, that means the useful comparison is not the monthly average but the upper tail of the distribution: a 32°C-plus reading is plausible in a hot, dry spell, while cloud, rain and marine air can keep the airport far below that range.[1][2][3]

Traders should watch the local forecast for Shanghai Pudong, particularly any shift towards a clear, stagnant air mass or, alternatively, plum-rain showers and thunderstorms that cap the afternoon high. The resolution source is Wunderground’s daily history page for ZSPD, and the market settles on the highest temperature recorded there during the day, so intraday timing matters as much as the headline forecast.[2] If a late weather system brings cloud and rain, the terminal reading can remain in the 20s even after a warm start; if conditions stay dry into the afternoon, the market can reprice quickly towards the upper 20s or low 30s.

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). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

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?

On Prediction Today, 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?

Prediction Today 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.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does it cost to trade on Prediction Today?

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

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.