US Extreme Weather and Climate Change Dashboard
Variables on this page
Every variable below is evaluated 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 own note says which).
Wildfire — Area Burned (MTBS)
AnnualMTBS satellite-measured (Landsat) burned area, Wildfire-type incidents only. Unit: acres burned per year.
MTBS's record starts in 1984, when the homogeneous Landsat-based methodology began — the full available record is already the reliable window. Excludes prescribed fire. A different metric from the NIFC fire-count panel below (area vs. number of fires) — MTBS's most recent year typically lags NIFC's by 1-2 years, so the two panels' latest years won't necessarily match. 1984, the first year of this series, is also the lowest; NIFC's independently-sourced series shows a similarly-shaped early dip, plausibly tied to the historically strong 1982-83 El Niño's fire-suppressing effect, though not independently confirmed. See the Methodology page.
Source: MTBS (Monitoring Trends in Burn Severity)
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MTBS has a real reporting lag: the most recent complete fire season available is typically 1-2 years behind the current calendar year, since satellite burn-severity mapping and QA for a full fire season take that long.
Wildfire — Fire Count (NIFC)
AnnualNIFC annual fire count. Unit: NIFC fires per year.
NIFC's live record extends back to 1983 (pre-1983 data used different reporting standards and isn't included) — the full available record is already the reliable window, so there's no earlier period to exclude here. The first two years (1983-84) read noticeably lower than 1985 onward; MTBS's independently-sourced series shows a similarly-shaped early dip, plausibly tied to the historically strong 1982-83 El Niño's fire-suppressing effect, though not independently confirmed. See the Methodology page.
Source: NIFC (National Interagency Fire Center)
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NIFC's live page states there is no official data prior to 1983 using current reporting standards, and no longer publishes pre-1983 figures — see the Methodology page.
* Flagged years (2004): NIFC's footnote says that year's acres figure (a different series from the fire count trended above) excludes North Carolina state-land reporting — incomplete, not silently normal.
Wildfire — Fire Weather (VPD)
AnnualA fire-WEATHER metric (national mean Vapor Pressure Deficit from gridMET), not a fire-outcome metric like every other wildfire panel -- an atmospheric-aridity measurement independent of fire suppression, fuel management, or wildland-urban-interface growth, and the metric the wildfire climate-attribution literature (Abatzoglou & Williams 2016) actually centers on. Unit: kPa.
A national CONUS mean is far more muted than any western-US-only VPD trend reported in the literature, since it blends the humid eastern half of the country (small VPD, small VPD trend) with the arid West, where most published anthropogenic VPD/fire-risk attribution work is concentrated. A deliberate national-vs-regional scope choice for consistency with the other series here, not an attempt to reproduce a western-US-specific published trend magnitude -- see the Methodology page.
Source: gridMET (University of Idaho Climatology Lab)
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Wildfire — High Fire-Weather-Stress Days
AnnualAnnual count of days whose national mean VPD exceeds that calendar day's 1979-2008 base-period 90th percentile -- a secondary, complementary view of the same fire-weather series above, analogous to how the wildfire page's other panels pair a raw mean with an exceedance-day count. Unit: days per year.
ETCCDI/CLIMDEX-style windowed calendar-day-of-year percentile threshold (Zhang et al. 2005), applied to day-of-year integers (not literal calendar dates -- a disclosed simplification around Feb 29). Base-period years are included in the per-year counts (standard ETCCDI convention: the threshold is fixed once from the base period, then applied across the whole record, including the base years). Secondary and complementary to the mean-VPD panel above, analogous to how the wildfire page pairs burned area with large-fire count -- a raw-mean and an exceedance-day-count view of the same underlying series.
Source: gridMET (University of Idaho Climatology Lab)
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Wildfire — Large-Fire Count (MTBS)
AnnualMTBS annual count of large (≥ 1,000 acre) Wildfire-type fires -- a large-fire-specific complement to NIFC's total fire count, which is dominated by small fires. Unit: large fires per year.
Distinct from the NIFC fire-count panel, which is dominated by small fires (tens of thousands/year) and can mask a trend in the large, climate-relevant fires specifically. The 1,000-acre threshold matches Dennison et al. (2014), 'Large wildfire trends in the western United States, 1984-2011,' Geophysical Research Letters -- a widely-cited MTBS-based large-fire cutoff -- and excludes only the smallest ~7.6% of MTBS's Wildfire-type records nationally (MTBS already only maps fires 500ac+ East / 1,000ac+ West by design). Shares the burned-area panel's reporting lag: the most recent year here is typically 1-2 years behind the current calendar year.
Source: MTBS (Monitoring Trends in Burn Severity)
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Wildfire — Fire Season Length (MTBS)
AnnualMTBS fire-season length, from large (≥ 1,000 acre) fire ignition dates (5th–95th percentile span, resistant to a single outlier fire). Unit: days (season span).
Season length is the 5th-95th percentile span of large-fire ignition day-of-year, chosen over the naive first/last ignition day because a single very-early or very-late outlier fire can otherwise blow the naive figure out to nearly the full year. Every 1984-2024 year has at least ~138 qualifying fires, so no year in this record is thin. Years with zero large fires are omitted here (no ignition-date distribution to summarize). NIFC cannot support this metric: its live table has no per-fire dates, only annual aggregates, so this is MTBS-only. Season length (temporal breadth) does not track fire-season severity 1:1, unlike large-fire count, which does. See the Methodology page.
Source: MTBS (Monitoring Trends in Burn Severity)
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