Highest temperature in Wellington on July 21?

Platform comparison

Market context

Wellington’s highest temperature on 21 July 2026 will be recorded at the Wellington International Airport Station, with the market resolving to the Celsius range containing that peak. The crowd currently assigns a 0% probability to any outcome other than the frontrunner, which Polymarket data shows as 12°C at 100% implied probability, leaving no room for alternative ranges like 7°C or below [1]. This near-certainty contrasts sharply with how traditional books such as Kalshi or Betfair would frame the same event: Kalshi typically uses decimal odds rather than implied probability, while Betfair and Smarkets operate on a decimal odds model with lower fees for high-volume traders but stricter KYC requirements than Polymarket’s global access.

Historically, mid-July highs in Wellington hover between 8°C and 14°C, with 12°C representing a median winter peak rather than an outlier. The 0% probability on alternative ranges suggests the market treats 12°C as a statistical lock, a stance that diverges from Smarkets’ more conservative pricing on similar weather events, where implied probabilities rarely exceed 90% without meteorological backing. Unlike Kalshi, which requires US residency and emphasises regulatory compliance, Polymarket’s permissionless structure allows this tight consensus to form without institutional oversight, potentially inflating confidence in the frontrunner.

Traders should monitor the daily Wunderground history for NZWN, the official resolution source, and watch for any sudden shifts in the South South Westerly wind pattern, which currently sits at 24 mph and could suppress temperatures below 12°C [2]. No scheduled announcements or climate dependencies are expected to alter the forecast, but real-time wind and cloud cover data will be critical as the settlement window closes at 12:00 UTC on 21 July. The divergence in fee structures—Polymarket’s 2% maker fee versus Betfair’s 5% commission on winnings—further shapes how liquidity concentrates on this near-certain outcome.

Sources: 1 · 2

Methodology

This page compares Highest temperature in Wellington on July 21? 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

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

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.

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.

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.