US Extreme Weather and Climate Change Dashboard
Variables on this page
This site evaluates every variable below over a full reliable-trend window against this site's combined "detected change" standard (IPCC's likelihood criterion plus a magnitude-vs-variability check -- see the homepage or Methodology for the full definitions). Shown as alternative ways of characterizing this same phenomenon -- some from independent sources, others a different construction on the same underlying data (each variable's note says which).
Winter Storms
AnnualNCEI Regional Snowfall Index, annual major-storm count. Unit: Category 3+ (major) storms per year.
This panel uses Category 3+ (major storms, n_major_plus) rather than the raw storm count, which likely conflates a real signal with growth in the observing network over time — see the Methodology page.
Source: NCEI Regional Snowfall Index (RSI)
Computing trend…
Winter Storms — Heavy Snowfall Days
AnnualStation-level physical snowfall extreme (mean days per year a station's snowfall crosses the station's 90th-percentile threshold), a direct complement to RSI's per-storm regional impact scoring. Unit: heavy-snow days per station.
Per-station 90th percentile of measurable-snow-day (1mm+) amounts, over the station's full available record -- adapted from the ETCCDI/CLIMDEX R95p "very wet days" convention (Zhang et al. 2011) rather than a fixed absolute threshold, so a naturally snowy station and a marginal-snow station are each judged against their own climate. Restricted to HCN stations with 100+ measurable-snow-day observations and 20+ years of record (a data-driven snowy-climate floor rather than a geographic cutoff), a fixed reference network so a rising station count can't inflate this series. This series excludes 2011-2014 rather than merely muting them due to a real, verified COOP manual-snowfall-reporting collapse in those years. See the Methodology page.
Source: NOAA GHCN-Daily, HCN reference stations (snowy-climate subset)
Computing trend…
Winter Storms — Cyclone Minimum Pressure
AnnualDirect central-pressure intensity of storms in this catalog affecting the US East Coast / western Atlantic. This catalog now demonstrably pre-filters toward already-significant/rapidly-deepening cyclones (see note) -- read this as the severity of storms significant enough to appear in it rather than a representative sample of all East Coast ETCs. Unit: hPa (lower = more intense).
This catalog's filename flags it as a 'select' file: reconstructing bomb-cyclone status from the raw tracks finds 64% of all Northern-Hemisphere-wide storms in it qualify as bomb cyclones (1+ Bergeron), versus ~7% in an unfiltered NARR-based climatology (Fritzen, Lang & Gensini 2021, J. Appl. Meteor. Climatol. 60(9)), which also found no significant East Coast bomb-cyclone trend. This page shows no bomb-cyclone frequency panel for that reason. Pressure and wind (this panel and the one below) measure the severity of whatever storms this pre-filtered catalog retained rather than a frequency -- but still describe this catalog's population rather than literally every East Coast storm. No detected change over 1979-2021 (Mann-Kendall p=0.965).
Source: CEDA extratropical cyclone track catalog (Gray et al. 2024)
Computing trend…
Winter Storms — Cyclone Peak Wind
AnnualPeak near-surface wind of storms in this catalog affecting the US East Coast / western Atlantic -- the metric most directly comparable to NCA5's Northeast-chapter 'increasing max wind speed since 1940' nor'easter finding. This catalog now demonstrably pre-filters toward already-significant/rapidly-deepening cyclones (see note), so read this as the severity of storms significant enough to appear in it rather than a representative sample of all East Coast ETCs. Unit: m/s.
This catalog's filename flags it as a 'select' file: reconstructing bomb-cyclone status from the raw tracks finds 64% of all Northern-Hemisphere-wide storms in it qualify as bomb cyclones (1+ Bergeron), versus ~7% in an unfiltered NARR-based climatology (Fritzen, Lang & Gensini 2021, J. Appl. Meteor. Climatol. 60(9)). A detected increase over 1979-2021 -- the metric most directly comparable to NCA5's Northeast-chapter nor'easter wind-speed finding -- though this record only reaches back to 1979, so it cannot confirm or refute NCA5's longer, since-1940 claim, and describes only the pre-filtered population inside this catalog.
Source: CEDA extratropical cyclone track catalog (Gray et al. 2024)
Computing trend…
RSI scores snowfall extent, amount, and population impact — it is a snowfall-impact index rather than a wind-speed or central-pressure based measure of extratropical-cyclone intensity. The RSI-based major-storm count at the top of this page does not confirm or refute NCA5's separate, regional finding that the strongest Northeast nor'easters show increasing max wind speed and hourly precipitation rate since 1940: that's a claim about storm intensity characteristics in one region, structurally different from — and not measured by — RSI's national snowfall-impact event count.
Four years tie for the record shown here — 1978, 1987, 2010, and 2013, each with 5 Category 3+ storms; 1978 (the January "Cleveland Superbomb") also holds the single highest individual-storm RSI value in the entire 1900–2025 catalog (predating the reliable-trend window shown, but a real fact about the fuller record).
See also: Ryan Maue maps every cyclone on Earth since 1979, including extratropical “bombs” and their central pressures, in hisStorm Atlasat bombcyclone.earth. His counts cover the whole globe and come from ERA5 reanalysis, not station observations, so they sit outside the US trend charts above.