Data sources & trust

Every number, and where it came from

This app doesn't forecast anything itself. It reads official sources, lines them up, and shows them to you. Here is exactly who supplies what, how often each one moves, and where each one lags behind live.

Providers

Who supplies what

Weather data providers, what each supplies, how often it updates, and a note about its limits
Provider	Supplies	Cadence	Note
NOAA National Operational Hydrologic Remote Sensing Center	Current snow cover and snow depth for the contiguous United States	Operational snow analysis; checked for updates every 30 minutes	Ground, airborne and satellite observations are combined with a snow model. The source’s analysis time and official depth legend are shown; Alaska and Hawaii are outside this product’s coverage.
Open-Meteo	Current conditions and forecasts for all fifty state capitals and for any city you search	Refreshed about every 10–12 minutes	Needs no account or key, so nothing secret is shipped to your browser.
National Weather Service (api.weather.gov)	Every active weather alert	Refreshed as the Service issues and cancels them	The only source of alerts in the app. None are ever added by us.
NOAA Weather Prediction Center	Surface analysis maps, fronts and high/low pressure positions	New analysis about every 3 hours	The coded bulletin is read and drawn as lines and letters on our own maps.
NOAA RCC-ACIS	Daily Recap observations, 1991–2020 normals, and daily records	Daily, finalized after the source completes its observations	Each figure carries its station, the station's historical coverage, and its source.
RainViewer	Rain and snow radar frames	New frames every few minutes	Frames are shown with the time each was captured.
NASA GIBS	Satellite cloud cover	Daily	Satellite clouds come from NASA GOES-East and run about an hour behind live.
Esri, OpenStreetMap, OpenTopoMap	The base maps underneath everything	Static basemaps	A dark basemap, satellite imagery, and a terrain option.

NOAA National Operational Hydrologic Remote Sensing Center
Current snow cover and snow depth for the contiguous United States
Operational snow analysis; checked for updates every 30 minutes
Ground, airborne and satellite observations are combined with a snow model. The source’s analysis time and official depth legend are shown; Alaska and Hawaii are outside this product’s coverage.
Open-Meteo
Current conditions and forecasts for all fifty state capitals and for any city you search
Refreshed about every 10–12 minutes
Needs no account or key, so nothing secret is shipped to your browser.
National Weather Service (api.weather.gov)
Every active weather alert
Refreshed as the Service issues and cancels them
The only source of alerts in the app. None are ever added by us.
NOAA Weather Prediction Center
Surface analysis maps, fronts and high/low pressure positions
New analysis about every 3 hours
The coded bulletin is read and drawn as lines and letters on our own maps.
NOAA RCC-ACIS
Daily Recap observations, 1991–2020 normals, and daily records
Daily, finalized after the source completes its observations
Each figure carries its station, the station's historical coverage, and its source.
RainViewer
Rain and snow radar frames
New frames every few minutes
Frames are shown with the time each was captured.
NASA GIBS
Satellite cloud cover
Daily
Satellite clouds come from NASA GOES-East and run about an hour behind live.
Esri, OpenStreetMap, OpenTopoMap
The base maps underneath everything
Static basemaps
A dark basemap, satellite imagery, and a terrain option.

House rules

How the app handles a number

Nothing is inventedEvery number on this site comes from the providers listed above. When a value is missing it is shown as missing — a dash, or "None on record" — never estimated to fill a gap.

Preliminary until finalizedA day's observations are marked Preliminary until the source finalizes them. Once finalized, the same card reads Final, so you always know how firm the number is.

A day belongs to its own place"Yesterday" is worked out in each station's own time zone. Honolulu and Anchorage each get their own yesterday rather than being forced onto one national date.

Every record names its stationA record is shown with the station that measured it, how many years that station has been reporting, and where the number came from. A station with a short history is honest about it.

Access & keys

Nothing secret ships to your browser

Keyless providers, called directlyThe services used today need no account or key, so the app can call them straight from your browser without hiding anything secret inside it.

A keyed provider stays on the serverIf a service that needs a key is ever added — a premium forecast, for instance — the call moves to server code that reads the key from project secrets. The key never appears in anything your browser downloads.

NOAA's Weather Prediction Center blocks automated requests, so the fronts bulletin is fetched by server code on your behalf rather than straight from the page.

Seeing the sources is one thing; seeing them on a map is another. The dashboard puts live conditions for all fifty states in front of you in a second.

Open the dashboard Feature tour