Rainfall and rainy days in 16 U.S. cities, 1991–2020 normals

What this dataset measures

Built to test the common belief that Seattle is the rainiest big U.S. city. The 16 stations cover wet East Coast and Gulf cities, the Pacific Northwest, and dry Western cities for contrast. Each city uses its primary NWS first-order station (the main airport; Central Park for New York), the stations most often quoted for each city's climate.

Geography

United States, Seattle, Washington

Unit of observation

One weather station (one city)

Update cadence

NOAA publishes new normals every 10 years; the next set (1996–2025 or 2001–2030) will replace these.

Curator

FactHub Research Team

Curated data tables

These related tables form this versioned dataset release. Each table has its own downloadable file and field definitions.

Annual precipitation normals by city

1991–2020 annual precipitation and rainy-day normals for 16 U.S. cities' main weather stations, sorted by annual precipitation.

Unit of observation: One NOAA weather station

View this table

rain-normals-1991-2020.csv text/csv · 1.1 KB (1,158 bytes)

6 field definitions

Field	Type	Meaning	Units	Value type
station_id	string	NOAA GHCN-Daily station identifier.	—	observed
station_name	string	NOAA station name as published.	—	observed
city	string	Short name of the city the station represents, added by FactHub.	—	derived
annual_precip_in	number	Annual precipitation normal (NOAA data type ANN-PRCP-NORMAL), rain plus melted snow.	inches per year	observed
rain_days_001in	number	Average number of days per year with at least 0.01 inch of precipitation (ANN-PRCP-AVGNDS-GE001HI).	days per year	observed
rain_days_010in	number	Average number of days per year with at least 0.10 inch of precipitation (ANN-PRCP-AVGNDS-GE010HI).	days per year	observed

Saved analyses

Sources

1. NOAA NCEI U.S. Climate Normals 1991–2020, annual/seasonal normals (Access Data Service) Primary source for every value

   Retrieved November 5, 2026. U.S. Government work (public domain). Allowed without restriction

   Reliability: Government. NOAA's National Centers for Environmental Information computes the official U.S. climate normals every decade from quality-controlled daily observations at National Weather Service stations. It is federally funded and has no stake in which city is rainier.

2. NOAA NCEI: U.S. Climate Normals overview and documentation Definitions and methodology of the normals

   Retrieved November 5, 2026. U.S. Government work (public domain). Allowed without restriction

   Reliability: Government. NOAA's documentation page for the 1991–2020 normals, describing how they are computed. Federally funded.

License: FactHub's selection, cleaning and combined tables are licensed under CC BY 4.0. Source data keeps the terms listed above (terms).

Limitations and reproducibility

Reproducible: Values were downloaded on 2026-11-05 from NOAA NCEI's Access Data Service (dataset normals-annualseasonal-1991-2020, data types ANN-PRCP-NORMAL, ANN-PRCP-AVGNDS-GE001HI and ANN-PRCP-AVGNDS-GE010HI) for the station IDs listed in the table, and copied without change apart from adding a short city name.

• Each city is represented by one station, usually its main airport. Rainfall can differ by several inches across a metro area; Seattle-Tacoma airport, for example, is wetter than some north Seattle neighborhoods.
• Normals are 30-year averages. Any single year can be much wetter or drier.
• Precipitation includes the water content of snow, so cold-climate totals (Chicago, Denver, Boston) count snowfall melted to water.
• A day with measurable precipitation counts any day with at least 0.01 inch, including a brief drizzle. The 0.10-inch column gives a stricter count.
• Portland, Ore., averages slightly more days with measurable precipitation (157.0) than Seattle (156.2), so Seattle is not first on that measure among all large U.S. cities.