Data Sources & Attribution

This site is built on public data. Below are the sources, with links and the attribution each one asks for.

NOAA / NCEI U.S. Climate Normals 1991–2020

First-freeze and last-freeze probability dates, snowfall normals, station names, and elevations come from the NOAA National Centers for Environmental Information 1991–2020 U.S. Climate Normals (Annual/Seasonal and Monthly products). NOAA NCEI U.S. Climate Normals.

Open-Meteo

The live 10-day forecast is provided by Open-Meteo. Weather data by Open-Meteo.com, licensed under CC BY 4.0.

National Weather Service API

Active watches and warnings, when shown, come from the U.S. National Weather Service public API (api.weather.gov).

City list

City names, coordinates, and populations come from a public U.S. Census–derived cities dataset, supplemented with a state-capitals table so every state is represented. State capital coordinates and population figures are from public records.

Guidance and thresholds

Prep steps and temperature thresholds paraphrase openly published guidance from government and industry sources — including the American Red Cross, University of Minnesota Extension, FEMA and the National Flood Insurance Program, national auto clubs, and equipment manufacturers. We summarize this guidance in our own words and do not reproduce copyrighted text.

Last updated: July 11, 2026.