Developers

Last updated 25 September 2026

The forecasts, alerts, river gauges and tides behind this site, as JSON anyone can call, and every alert, calendar and article as a feed. No key and no account. The rules are short: cache what you fetch, identify yourself, and credit the agencies the data comes from.

Terms of use

• Free, including commercial use. Call these endpoints from an app, a website, a script or a newsroom tool, and show what they return, as long as the credit below goes with it.
• Not for decisions about safety. Everything here is a copy of what government agencies publish, read on a schedule, and it can be late or missing. Warnings reach the public through the National Weather Service, Wireless Emergency Alerts and NOAA Weather Radio; an app that relays alerts must not suggest it replaces them. The terms of use apply to the API as they do to the site.
• Do not present it as official. Nothing here is a product of the National Weather Service or any agency, and it must not be labeled as one.
• No warranty and no service level. The endpoints listed on this page are the ones meant to stay put. If one has to change, the change is listed here first. Anything under /api/ that is not on this page is internal: it can change or disappear without notice, and it does not answer other sites' browsers.

Usage expectations

• Cache. Every answer carries a Cache-Control header saying how long it stays good: a minute for alerts, five to ten minutes for forecasts, an hour or a day for reference lists. Asking again sooner returns the same answer.
• Keep it modest. There is no hard quota today. A few requests a minute per user of your product, or a few hundred an hour for a server that polls, is fine. Clients that put unusual load on the site, crawl coordinates in bulk or ignore the cache headers may be blocked without notice. For bulk data, go to the agency's own source, linked under each endpoint.
• Identify yourself. From a server, send a User-Agent that names your product and a way to reach you, as the National Weather Service asks of its own API users. Browsers send their own and cannot change it; that is fine.
• From a browser. The endpoints below send Access-Control-Allow-Origin: *, so a page on any site can read them.
• Coordinates are decimal degrees, WGS 84, longitude negative in the west. Up to four decimals are used; more are rounded.

Attribution

The data is public, but the agencies ask to be named, and this site asks to be linked. Show a line such as "Data: NOAA National Weather Service, via WeatherOverTime" with a link to weatherovertime.com, naming the source each endpoint lists:

Endpoints

All are GET on https://weatherovertime.com and answer JSON. Temperatures are degrees Celsius, winds kilometers per hour, precipitation millimeters and times ISO 8601 unless a field says otherwise. An error is an HTTP status with a JSON body such as {"error": "bad_point", "message": "Pass lat and lon."}: 400 for a malformed request, 404 for nothing there, 502 when the agency did not answer (try again in a minute).

GET /api/forecast/point?lat=41.5868&lon=-93.625

{
  "source": "nws",
  "point": { "lat": 41.5868, "lon": -93.625, "wfo": "DMX", "gridX": 73, "gridY": 49,
             "tz": "America/Chicago", "radar": "KDMX", "zone": "IAZ060", "county": "IAC153",
             "near": { "city": "Des Moines", "state": "IA", "km": 0, "bearing": 0 } },
  "grid": { "updated": "...", "validFrom": "...", "validHours": 170, "series": { ... } },
  "periods": [ { "name": "This Afternoon", "start": "2026-09-25T13:00:00-05:00",
                 "temperatureC": 17.8, "pop": 83, "windKmh": [12.9, 12.9], "windDir": "ESE",
                 "short": "Rain Showers", "detailed": "Rain showers. Mostly cloudy, ..." } ],
  "hourly": [ { "start": "2026-09-25T13:00:00-05:00", "temperatureC": 16.7, "dewpointC": 16.1,
                "rh": 97, "pop": 83, "windKmh": 11.3, "windDir": "ESE", "short": "Rain Showers" } ],
  "fetchedAt": "2026-09-25T18:34:06.137Z"
}

GET /api/forecast/alerts?lat=29.21&lon=-81.02

{ "alerts": [ { "id": "urn:oid:2.49.0.1.840.0....", "event": "Rip Current Statement",
                "severity": "Moderate", "urgency": "Expected", "certainty": "Likely",
                "sent": "...", "onset": "...", "ends": "...", "expires": "...",
                "senderName": "NWS Melbourne FL", "areaDesc": "Coastal Volusia, FL",
                "headline": "...", "description": "...", "instruction": "...",
                "tags": [], "hail": null, "gust": null, "tornado": null, "motion": null } ],
  "fetchedAt": "2026-09-25T18:34:06.137Z" }

GET /api/alerts?bbox=-98,36,-90,44

{ "updated": "2026-09-25T18:34:09.100Z", "count": 12,
  "alerts": [ { "id": "https://api.weather.gov/alerts/urn:oid:...", "event": "Flood Warning",
                "severity": "Severe", "sent": "...", "effective": "...", "expires": "...",
                "areaDesc": "...", "polygons": [ [ [ -93.61, 41.60 ], ... ] ],
                "ugc": [ "IAC153" ], ... } ] }

GET /api/forecast/nbm?lat=41.5868&lon=-93.625

{ "run": "2026-09-25T12:00:00Z", "domain": "conus",
  "cell": { "col": 1335, "row": 755, "lat": 41.5868, "lon": -93.625 },
  "series": { "temp": { "t": [ 1790341200000, ... ], "v": [ 17.1, ... ] }, "maxt": { ... }, ... } }

GET /api/forecast/climate?station=USW00014933

{ "station": "USW00014933", "first": "1945-07-01", "last": "2026-09-17",
  "normalHigh": [ ... 366 values ... ], "normalLow": [ ... ], "normalPrecip": [ ... ],
  "recordHigh": [ ... ], "recordHighYear": [ ... ], "recordLow": [ ... ], ... }

GET /api/rivers/near?lat=41.5868&lon=-93.625

{ "gauges": [ { "lid": "DEMI4", "river": "Raccoon River", "location": "Des Moines Fleur Dr",
                "state": "IA", "km": 1.6, "status": "no_flooding", "forecastStatus": "action",
                "observed": 5.2, "units": "ft", "flood": 12 } ] }

GET /api/tides/near?lat=32.78&lon=-79.93

{ "tides": { "station": { "id": "8665530", "name": "Charleston", "state": "SC",
                          "km": 0.6, "path": "/tides/south-carolina/charleston-8665530/" },
             "events": [ { "t": "2026-09-25T11:23:00.000Z", "ft": 5.838, "high": true }, ... ] } }

GET /api/sites

[ { "id": "KABR", "name": "Aberdeen", "lon": -98.41305, "lat": 45.45583, "elevM": 397 }, ... ]

Feeds

Atom 1.0 and RSS 2.0, for a feed reader or anything that reads either. Each item's id is permanent: an alert's is its CAP identifier, so an update to an alert is a new item and a reader never shows the same product twice. Alert feeds are cached a minute.

The state and county parts are the alerts pages' own: the address of /alerts/iowa/polk-county/ gives /feeds/alerts/iowa/polk-county.atom. The town part is the forecast page's address without /forecast/. Pages with a feed announce it in their <head>, so most readers find it from the page itself.

Calendars

iCalendar (RFC 5545) files to subscribe to in Apple Calendar, Google Calendar, Outlook or any calendar app, so they keep themselves current. Open one with webcal:// in place of https:// to subscribe rather than import a copy.

A calendar app refreshes a subscription on its own schedule, from every 15 minutes to once a day, so an alert calendar is for planning, not for warnings.

What is not offered

The radar data itself (/data/), the radar archive, map tiles, the address search and the lightning feed are not open to other sites: each costs this site real storage reads or passes through to a service that did not agree to carry other sites' traffic. Their sources are open, and better used directly: NEXRAD Level II and GOES on the NOAA Open Data Dissemination program, the National Weather Service API, and the Census Geocoder.

Contact

Questions, a use that needs more than this page allows, or a change you need notice of: contact@weatherovertime.com.