6% — Rain in Seattle in Apr 2026
Leader: Above 2 inches at 6% · Kalshi 6% · 5 contracts · $5K volume · medium confidence
Updated 2026-06-26 09:42:32 UTC

Tracks the leading outcome in a winner-take-all prediction market set with 5 outcomes.

Why this matters:
This probability reflects the chance that Seattle will receive more than 2 inches of rain during April 2026. The 35% reading suggests below-average rainfall expectations for that month. Seattle's April precipitation is shaped primarily by atmospheric river frequency and the transition between spring and early summer weather patterns. Historical April averages for Seattle range around 3.7 inches, so this contract pricing implies markets are discounting the likelihood of above-normal rainfall. The resolution will be determined by actual precipitation measurements from Seattle-Tacoma International Airport or equivalent official sources at the end of April. Key drivers include the strength of Pacific storm systems in spring, sea surface temperature anomalies in the North Pacific, and broader climate patterns that influence seasonal moisture delivery to the Pacific Northwest.

Key factors:
- Historical April precipitation in Seattle averages 3.7 inches; markets pricing 35% for >2 inches suggests expected conditions below historical norms
- Sea surface temperature patterns in the North Pacific during winter-spring months influence spring storm frequency and intensity reaching the Pacific Northwest
- The El Niño/La Niña phase heading into spring 2026 typically correlates with precipitation deviations from normal in the Pacific Northwest
- April sits at the transition between wet season decline and drier summer conditions; storm track positioning determines whether systems reach Seattle
- Official precipitation measurements will be reconciled against NOAA or National Weather Service data for the Seattle-Tacoma region to determine contract settlement

Contracts:
- Rain in Seattle in Jun 2026?: Above 2 inches — 6¢ Kalshi $4K (weight 77%)
- Rain in Seattle in Jun 2026?: Above 6 inches — 4¢ Kalshi $0 (weight 0%)
- Rain in Seattle in Jun 2026?: Above 3 inches — 3¢ Kalshi $1K (weight 23%)
- Rain in Seattle in Jun 2026?: Above 4 inches — 3¢ Kalshi $0 (weight 0%)
- Rain in Seattle in Jun 2026?: Above 5 inches — 3¢ Kalshi $0 (weight 0%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-06-26T09:20:51.013Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "6% per prediction markets (SimpleFunctions, June 2026)"
Canonical: https://simplefunctions.dev/answer/rainseam
Full data: https://simplefunctions.dev/api/public/query?q=Rain%20in%20Seattle%20in%20Apr%202026
Provider: SimpleFunctions — https://simplefunctions.dev