SimpleFunctions
Winner-take-all answer·4 source contracts·Kalshi 4·refreshed just now·Closes Dec 1, 2026 · 99d

When will the next Category 5 hurricane form

Leader sits at 55% across 4 bound outcomes, runner-up at 19%. This is a winner-take-all market — the headline is the leader’s price, not an arithmetic mean.

Leader probability

55%

Before Dec 1, 2026

runner-up 19¢leader 55¢

Outcomes

4

winner-take-all

Runner-up

19¢

Before Nov 1, 2026

Spread

36pp

contested

24h volume

$200

thin orderbook

Closes

Dec 1, 2026

99 days

Venue

Kalshi

4 bound

30-day trend

0%50%100%-30d-3w-2w-1wtodayBefore Dec 1, 2026: 33% (15 days, 15 points)Before Dec 1, 2026: 33% on 2026-08-23Before Nov 1, 2026: 16% (15 days, 10 points)Before Nov 1, 2026: 16% on 2026-08-23Before Oct 1, 2026: 10% (15 days, 15 points)Before Oct 1, 2026: 10% on 2026-08-23
Before Dec 1, 202633¢Before Nov 1, 202616¢Before Oct 1, 202610¢
Top 3 candidates by current price · 15d

Bracket family

How the bracket ladder is priced.

Each row is one outcome on the venue. Sorted by 24h volume — the heaviest book is at the top.

Analysis

This probability measures the chance that a Category 5 hurricane will form before September 1, 2026—just three weeks away. Markets currently estimate this at 4%, reflecting the rarity of Category 5 storms and the advanced stage of the 2026 Atlantic hurricane season. The assessment depends on current sea surface temperatures, atmospheric conditions, and historical frequency: Category 5 hurricanes form in only a small fraction of Atlantic seasons. If tropical activity accelerates significantly in late August, or if satellite data shows unusual ocean warming patterns, this probability would likely rise. The main near-term catalyst is early September itself—if no Category 5 forms by September 1, the market will shift focus to the October 1 and November 1 contract windows, when hurricane season typically peaks. Real-time monitoring of developing tropical systems and sea surface temperature anomalies will be the primary drivers of probability movement.

  • Only 3 weeks remain until the September 1 deadline, and no major tropical systems are currently forecast to rapidly intensify to Category 5 strength
  • Historical data shows Category 5 hurricanes are rare events; fewer than 20 have formed in the Atlantic basin since 1850, with clustering in certain decades
  • Current Atlantic sea surface temperatures and atmospheric indicators would need to shift substantially to support rapid intensification
  • September 1 serves as the immediate resolution date; if it passes without a Category 5, market focus shifts to later-season windows when conditions typically favor stronger storms
  • Operational hurricane forecasting models and real-time satellite imagery of tropical systems will provide the clearest signals for probability revision

What moved the line

  • Aug 21Before Oct 1, 202613pp207¢ · Kalshi
  • Aug 20Before Oct 1, 202610pp1020¢ · Kalshi
  • Aug 23Before Dec 1, 20269pp2433¢ · Kalshi
  • Aug 17Before Nov 1, 20267pp613¢ · Kalshi
  • Aug 17Before Dec 1, 20266pp915¢ · Kalshi

Recently closed in climate

These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.

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How we compute these odds

SimpleFunctions aggregates live prediction-market contracts from Kalshi and Polymarket. Each slug groups contracts that resolve on the same underlying event, identified by venue event_id.

For binary slugs, the headline probability is the liquidity-weighted mid-price across all bound contracts. For multi-outcome slugs (e.g. elections with 3+ candidates), the headline is the leader’s price; we never arithmetically average disjoint outcomes — that would produce a number with no real-world meaning.

Snapshots refresh every 5 minutes during market hours; daily aggregates are computed at 04:00 UTC. The 30-day sparkline is drawn from per-ticker daily means stored in market_indicator_daily; 24h delta and movement events are derived from the same source.

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