SnowDates

Methodology

Data pipeline

Each tracked city is matched to a nearby NOAA weather station (preferring long-record airport stations within about 60 km) with daily snowfall coverage across the normals window. Daily snowfall observations come from NOAA's GHCN-Daily dataset, accessed through the ACIS web service operated by NOAA's Regional Climate Centers.

Definitions

  • Snow season: July 1 through June 30. Statistics cover the 30 seasons from 1990–91 through 2019–20, matching NOAA's 1991–2020 climate normals window.
  • Measurable snow: a daily snowfall total of at least 0.1 inch. Trace amounts count as zero.
  • Average first/last snowfall: the median day-of-season of the first (or last) measurable snowfall across seasons that had measurable snow. Medians resist skew from freak early or late storms.
  • Season length: days between the average first and average last snowfall dates.
  • Average annual snowfall: the mean of seasonal snowfall totals across quality-checked seasons.
  • "Early/late" chips: the most recent season's actual first-snowfall date compared against the 30-year normal.

Quality controls

  • Seasons missing more than 25 daily observations in the November–March core window are discarded.
  • Cities need at least 22 usable seasons to publish date normals; otherwise an alternate station is used or the city is dropped.
  • Cities with measurable snow in fewer than 15 of 30 seasons are shown as rare-snow cities without date normals.

Snow Score

The letter grade reflects a city's percentile of average annual snowfall among all tracked cities: A+ (≥95th percentile), A (≥85th), A− (≥70th), B+ (≥50th), B (≥30th), C (below 30th or effectively no snow).

Ski resorts

Resort opening/closing dates, elevations, and snowfall figures are curated editorial estimates based on typical historical seasons and resort-published information — NOAA does not track resort operations. Actual dates vary every year with conditions.

ZIP code search

ZIP searches use U.S. Census ZCTA centroids: each ZIP is mapped to the nearest tracked city by straight-line distance, so results show the closest available station data rather than ZIP-specific measurements.