NWS Grid Forecast Period Evidence API

Read selected forecast values for known US grid cells. Each period row includes start/end timestamps, day/night flag, temperature with its source unit, wind text and short forecast. Useful for a weather dashboard or forecast-data QA; this is a bounded dataset request, not an emergency warning or notification system.

At most3 office/grid pairs and14 periods per grid, one api.weather.gov/gridpoints/office/x,y/forecast request each. Grid IDs must come from NWS; the Actor does not convert an address/latitude into a grid or claim global coverage. First source periods are locally capped and truncation makes complete=false. Public source data can be delayed, revised, unavailable or uncertain; quoted forecasts remain forecasts. No radar, personal location, alert subscription, images, background refresh, guarantee of safe conditions or added interpretation. Generated forecast details outside selected fields are not tracked. No unit conversion: Fahrenheit/Celsius stays labelled. Period identity includes grid and forecast start; changed dates produce different identities, and absent periods are not deletion proof. Source Cache-Control is exposed so clients can respect caching.

Quick start

{"grids": [{"office": "TOP", "x": 31, "y": 80}], "maxPeriodsPerGrid": 2}

Pricing and budget

0.0005 USD per emitted forecast period observation (0.5 USD per1000), plus0.005 USD startup at default256MB. Higher memory can multiply startup events; check effective Store pricing. Failed/empty sources do not emit result charges; startup can still apply. At zero result budget, input validation occurs but no upstream request is sent, and rowsAvailable is null (unknown). A positive budget can request the bounded source set before output; emission stops at the result cap and complete=false/PARTIAL_BUDGET reports truncation.

Snapshot, integration and limits

Use dataset rows together with OUTPUT and SNAPSHOT. Pass SNAPSHOT.previousHashes as previousHashes in a later run. NO_BASELINE/FIRST_SEEN/UNCHANGED/CHANGED compare only selected metadata including itemKey and sourceUrl; missing records are not deletions. FIRST_SEEN means absent from the supplied baseline. There is no persistent hidden state or automatic polling. Export JSON/CSV/Excel through the default dataset.

API example: POST https://api.apify.com/v2/actors/soilair~nws-grid-forecast-period-evidence-api/runs with your Apify Authorization header and the JSON input above. Poll the returned run; read dataset items and OUTPUT/SNAPSHOT records using its store IDs. Do not place tokens or confidential data in input. No upstream key is needed. Results live in Apify run storage according to retention; no separate analytics service.

Only fixed HTTPS provider endpoints are constructed from validated identifiers. Public-IP DNS validation, pinned connections, TLS hostname verification,2MiB decoded responses, approximately95 seconds of network budget, at most5 same-provider redirects. Official API calls are distinct from website crawling; no arbitrary URLs or HTML pages. No linked documents/files are fetched. Queries are sequential with1-second spacing. Provider403/429 or Retry-After stops later calls; retry instructions are reported and no retry/proxy/circumvention is attempted. Shared IP limits and changes to upstream services can still block runs. Caller must respect provider headers and cache/reduce repeated requests. Text is data and should not be executed.

Developed with AI assistance. Tests and live/cloud comparisons qualify the selected-field contract; they do not prove commercial demand, provider uptime or a legal/license determination. Support: share a run ID and expected fields, without credentials or private material.

References: https://www.weather.gov/documentation/services-web-api