Danger Season 2025 microsite methodology

The Danger Season 2025 microsite integrates National Weather Service (NWS) alerts, population data, social disadvantage metrics from the Climate & Economic Justice Screening Tool (CEJST), Climate Central’s Climate Shift Index (CSI), and EPA/AirNow’s Air Quality Index (AQI). The methodology focuses on the period from May to October, identifying counties under extreme weather alerts or experiencing unhealthy air quality. It calculates four daily indicators: the total population facing alerts, the percentage of disadvantaged people affected, the percentage of the population facing at least one alert, and the proportion of extreme heat alerts attributable to climate change. The scope includes the contiguous United States, Alaska, Hawai'i, Puerto Rico, and the U.S. Virgin Islands, though certain datasets like CSI and AQI have specific geographic gaps.

• The Danger Season web feature tracks a specific set of National Weather Service (NWS) alerts, including coastal flood, flood, flash flood, lakeshore flood, hurricane, storm, storm surge, inland tropical storm, excessive heat, heat, extreme heat, and fire weather.
• The project identifies 'dangerous air quality' as any county where the mean NowCast AQI for PM2.5 equals or exceeds 100, which corresponds to the 'Unhealthy for Sensitive Groups' category.
• To determine the influence of climate change on heat, the methodology uses Climate Central’s Climate Shift Index (CSI), specifically subsetting values of 1 or greater, which indicate a moderate, strong, very strong, extreme, or exceptional influence.
• Social disadvantage is determined using the Climate & Economic Justice Screening Tool (CEJST), which uses a binary variable to designate Census Tracts based on burdens across categories such as energy burden, pollution, and health.
• There are significant data gaps for air quality monitoring; AQI data is unavailable for Alaska, Hawaii, Puerto Rico, the United States Virgin Islands, and 134 counties within the contiguous United States.
• The Climate Shift Index (CSI) data is limited to NOAA climate divisions covering the contiguous United States and does not include Alaska, Hawaii, Puerto Rico, or the United States Virgin Islands.

APA

Union of Concerned Scientists (2025). Danger Season 2025 microsite methodology. https://www.ucs.org/sites/default/files/2025-05/danger-season-microsite-methodology.pdf

Chicago

Union of Concerned Scientists. Danger Season 2025 microsite methodology. 2025. https://www.ucs.org/sites/default/files/2025-05/danger-season-microsite-methodology.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Danger Season 2025 microsite methodology |date=May 2025 |url=https://www.ucs.org/sites/default/files/2025-05/danger-season-microsite-methodology.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2025danger, author = {{Union of Concerned Scientists}}, title = {{Danger Season 2025 microsite methodology}}, institution = {Union of Concerned Scientists}, year = {2025}, month = may, url = {https://www.ucs.org/sites/default/files/2025-05/danger-season-microsite-methodology.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }