Data sources and attribution
Effective August 22, 2026
This page lists the sources behind every figure on WeatherTotals, what we take from each, and how we name them. Each figure on the site carries its own source and observation time.
Sources
| Source | What we take | How often | Licence |
|---|---|---|---|
| National Weather Service API (api.weather.gov) | Active alerts (winter, etc.), gridded cloud cover forecasts for dark-sky spots | Live, checked every 15 minutes | US public domain |
| NOAA Space Weather Prediction Center (services.swpc.noaa.gov) | Planetary Kp index (1-minute estimated and 3-hour official), 3-day Kp forecast | Every 15 minutes | US public domain |
| Iowa Environmental Mesonet of Iowa State University (mesonet.agron.iastate.edu) | Feed of NWS Local Storm Reports (spotter snow, rain, hail reports) | Live during events | Public domain; IEM asks for attribution |
| NOAA National Centers for Environmental Information (ncei.noaa.gov) | GHCN-Daily station observations (season to date, records) and U.S. Climate Normals 1991-2020 (averages) | Daily | US public domain, with citation |
Source notes
The National Weather Service API provides current alerts and the cloud cover data we use to estimate whether aurora will be visible at dark-sky locations. We check it every 15 minutes.
The NOAA Space Weather Prediction Center gives us the planetary Kp index, both the 1-minute estimated value and the 3-hour official value, plus a 3-day forecast. This is the main measure we use for aurora strength.
The Iowa Environmental Mesonet of Iowa State University aggregates Local Storm Reports filed by NWS offices. These are spotter reports of snow, rain and hail, and we use them for immediate event totals. IEM asks for attribution, and we name them on every figure that uses their feed.
For season-to-date totals and records, we use daily observations from GHCN-Daily, maintained by NOAA National Centers for Environmental Information. Averages come from the U.S. Climate Normals 1991-2020, also from NCEI. We update these daily.
Later modules will add snow data from the NOHRSC National Snowfall Analysis, a NOAA product. For hail, they will use reports from the NWS Storm Prediction Center and the storm events database maintained by NCEI.
Public domain notice
The government-produced weather and aurora material on this site is prepared by NOAA offices, including the National Weather Service. Under 17 U.S.C. 105, those works are not subject to copyright in the United States. We give this notice under 17 U.S.C. 403. The material identified includes Local Storm Reports, alerts, gridded forecasts, Kp index values and forecasts, GHCN-Daily observations, and climate normals.
Citation
When we use GHCN-Daily data, the citation is: Menne, M.J., I. Durre, B. Korzeniewski, S. McNeill, K. Thomas, X. Yin, S. Anthony, R. Ray, R.S. Vose, B.E. Gleason, and T.G. Houston (2012): Global Historical Climatology Network - Daily (GHCN-Daily), Version 3. NOAA National Centers for Environmental Information.
What we add
We compile the raw data into state and city totals, compute season-to-date figures, rank them, and add timestamps. The compilation and presentation are our work; the underlying numbers come from the original sources.
Names and endorsement
We name NOAA, the National Weather Service, the Space Weather Prediction Center, the National Centers for Environmental Information, and the Iowa Environmental Mesonet solely to credit the source of each figure. This does not imply endorsement by or affiliation with any of them, and we do not use their logos.
Reuse and errors
If you reuse our numbers, cite the page URL and the original source. To report an error, use the contact page. A snapshot is all an "as of" time represents: the source feeds behind it can run late, be revised, or go down.