Highest temperature in Istanbul on July 22?

Platform comparison

Market context

Istanbul Airport’s highest reading on 22 July is likely to land in the low 30s Celsius, which is the key band this market is effectively testing. July normals are hot but not extreme: one weather reference puts Istanbul’s typical July high at about 29°C, with the daily high and low averaging 29°C and 21°C respectively[2]. Against that backdrop, the crowd’s 0% YES framing is less a statement about the weather itself than about how the market has been bucketed or priced; the live Polymarket interface currently shows 31°C as the frontrunner at 90%, with 32°C at 10%[1].

For a power-user, the practical edge is in treating this as a data-scrape problem rather than a narrative one. The resolution source is NOAA’s Istanbul Airport timeseries, and the market settles on the highest value in the Temp column for 22 July, then waits until the first reading for the following day is published before it can resolve. Programmatically, that means polling the NOAA table, switching to metric units, extracting every timestamp for the date, and taking the daily maximum rather than the afternoon snapshot. The main catalysts are the day’s actual diurnal peak, any late-day heat spikes, and the publication timing of the next day’s first NOAA data point, which can delay settlement even after the temperature is already known[1].

Sources: 1 · 2

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Polymarket Review UK. 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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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.