FernWX doesn’t generate weather data. Here’s where it actually comes from.
FernWX collects, stores, and presents weather and environmental data from named third-party providers. This page lists each provider FernWX relies on and the attribution or licensing terms it publishes for reusing that data.
Mandatory attribution
These providers publish terms that require specific credit — exact wording, a linked mark, or both — wherever their data is shown, independent of whether FernWX is free or paid.
Apple WeatherKit
Apple requires the "Weather" attribution mark and a link to Apple’s data source attribution page wherever WeatherKit-derived data is shown. Weather alerts specifically must also name the issuing meteorological agency (e.g. NOAA) and link to Apple’s alert-details page; alert text may not be modified or obscured.
Apple Weather data sourcesOpen-Meteo (Forecast + Air Quality)
Licensed under CC BY 4.0. Requires the text "Weather data by Open-Meteo.com" linked to open-meteo.com wherever the data is shown — on the free tier and the paid commercial tier alike (upgrading removes the free tier’s non-commercial-use restriction, not the attribution obligation). The Air Quality API additionally carries a separate, mandatory citation to CAMS — the Copernicus ATMOSPHERE MONITORING Service, which is a different Copernicus service from the Climate Change Service (C3S) and takes a different citation. Open-Meteo requires "a clear attribution to CAMS ENSEMBLE data provider as well as a reference to Open-Meteo"; the full form it publishes credits the contributing institutes and ends "CAMS European air quality forecasts, ENSEMBLE data. Copernicus Atmosphere Monitoring Service (CAMS) Atmosphere Data Store (ADS)."
Open-Meteo licenseTomorrow.io
Requires "Powered by Tomorrow.io" linked to tomorrow.io near any displayed or derived data, on every tier. Commercial use is only permitted under a paid commercial Order (free/evaluation tiers forbid it), and their terms restrict storing "unaltered Datafeed" absent an Order that explicitly permits it — see the operator caveat below.
Tomorrow.io terms of serviceVisual Crossing
Metered commercial plan. Visual Crossing requires attribution ("Powered by Visual Crossing Weather", linked, placed near the data) on the Professional and Metered tiers; Corporate and Enterprise tiers carry no attribution requirement. FernWX collects the Timeline API (metric units) as an experimentation source; usage is quota-capped server-side. Their §10 gates storage by license level but opens "Except for personal use of the licensee" — which is what FernWX is today. Note that Visual Crossing publishes TWO terms documents at near-identical URLs: /weather-service-terms/ (singular) defines "Raw Weather Data" and restricts it from being readily exportable, while /weather-services-terms/ (plural, linked below) does not. Which governs the metered plan is unresolved — see the 2026-08-05 provider-terms bulletin.
Visual Crossing termsWeatherAPI.com
Free-tier users must "credit WeatherAPI.com by name or brand logo as the source of the data" for all uses; no paid-tier attribution requirement is stated in the public terms. Their terms also cap caching: current conditions 60 minutes, forecast data 24 hours, historical data no restriction — so the 2010-present historical backfill is the explicitly permitted product, while permanently retaining forecasts in order to score them later sits in tension with the 24-hour figure. Selling the raw weather data on is forbidden, and the API key may not be shared, transferred, or sublicensed to any third party.
WeatherAPI.com termsXweather (Vaisala)
Commercial PAYG free tier (15,000 weighted credits/month). Attribution to Xweather/Vaisala is required on public surfaces. FernWX has landed the client and product catalog but deliberately collects nothing yet — Xweather is intentionally absent from the default source list until the storm-gated lightning collector exists, so no account is shown an enabled provider that never collects.
Xweather documentationThe Weather Company
Standard Weather APIs under a Sales Enablement Evaluation entitlement (ENT0011896), live 2026-08-03 to 2026-09-02. Attribution is per-product rather than blanket — the Lightning StrikeZone and Local Storm Reports references state it is NOT required — so re-check the specific product doc in docs/providers/weather-company/ before publishing one to a public surface. Two things about this source are unresolved and are tracked in the 2026-08-05 provider-terms bulletin: whether the evaluation permits retaining collected data after expiry (no public document governs this entitlement), and whether IBM or Francisco Partners — who completed their acquisition of The Weather Company in February 2024 — governs the terms.
The Weather CompanySynoptic Data / CWOP (Citizen Weather Observer Program)
Legacy source — active Synoptic collection is currently disabled (the trial expired) and live CWOP/mesonet observations now come from NOAA MADIS; this credit is retained for previously aggregated Synoptic data. FernWX’s commercial license requires "Data Aggregated by Synoptic" (hyperlinked to synopticdata.com) on the primary page where observations are shown. Raw station-level data may not be redistributed without Synoptic’s prior written approval; derived/aggregated summaries may be shown freely. CWOP community station data is community-observed, provisional, and QC-tagged.
Synoptic Data terms & conditionsPublic domain sources
U.S. federal government works carry no copyright under 17 U.S.C. § 105. Attribution here is a courtesy FernWX follows, not a legal requirement.
National Weather Service (NWS) / NOAA
U.S. government work under 17 U.S.C. § 105 — public domain, no copyright, unrestricted commercial use. NOAA asks only that users not imply endorsement or present altered content as official government material; FernWX credits "National Weather Service" as a courtesy.
weather.gov disclaimerNOAA MADIS (Integrated Mesonet)
Same public-domain status as other NOAA products. NOAA confirmed FernWX has public access only via public HTTPS surfaces (FTP retired); no additional licensing conditions apply beyond standard NOAA attribution norms.
MADIS public dataStorm Prediction Center (SPC)
A NOAA office; categorical outlooks are public domain. FernWX credits "SPC" by name rather than a generic "NOAA" attribution.
Storm Prediction CenterNational Hurricane Center (NHC)
A NOAA office; tropical cyclone advisories, forecast tracks, and cones are public domain (US federal government work). Forecast geometry is served from NOAA’s ArcGIS MapServer. FernWX credits "NHC" by name, and treats cones and tracks as forecasts — official NWS watches and warnings remain the authoritative trigger.
National Hurricane CenterAviation Weather Center (AWC)
A NOAA office; glossary/definition text reused for the Discussions "Learner’s Mode" tooltips is public domain and freely reusable.
Aviation Weather CenterNOAA Climate Prediction Center (CPC) — ENSO indices
Weekly Niño-region sea-surface temperatures, ONI, and RONI are public-domain U.S. government work. Collected once for the deployment rather than per account — these rows carry no account or location ownership and are shared climate context. FernWX preserves the CPC dataset identity, climatology metadata, and retrieval provenance.
NOAA Climate Prediction CenterNOAA IGRA (Integrated Global Radiosonde Archive)
IGRA v2.2 sounding observations are public-domain NOAA/NCEI work. FernWX preserves station, cycle, archive identifier, and retrieval provenance so an imported sounding can always be traced back to its source record.
NOAA NCEI IGRANOAA SURFRAD (Surface Radiation Budget Network)
Ground-truth solar irradiance from the nearest active SURFRAD station — public-domain U.S. government work. NOAA requests, but does not require, the NCEI C00540 dataset citation; FernWX treats that as a courtesy credit rather than a license term.
NOAA SURFRADUSGS (U.S. Geological Survey)
Hydrology gauge data (streamflow, gauge height) is a public-domain U.S. government work. USGS’s own suggested credit line is "U.S. Geological Survey, Department of the Interior/USGS."
USGS Water ServicesIEM (Iowa Environmental Mesonet, Iowa State University)
Radiosonde/upper-air archive data originates from NOAA sources and is public domain. IEM itself is Iowa State University, not a federal agency, and its own disclaimer asks that attribution "would be appreciated" — a courtesy, not a license term.
IEM disclaimerAI synthesis
OpenRouter, xAI (Grok), and OpenAI
FernWX routes AI synthesis (text explanations, read-aloud TTS) through OpenRouter to underlying model providers. No provider’s terms require attributing them by name in end-user UI. Every synthesized surface in FernWX is labeled as synthesis, not Weather Ledger truth, which covers current disclosure best practice even without a formal legal mandate.
OpenRouter termsThis page was assembled from each provider’s publicly published attribution/terms pages, first on 2026-07-06 and re-verified clause-by-clause on 2026-08-05. It has not been reviewed by legal counsel and is not a substitute for reading FernWX’s actual signed agreements with any of these providers. Full findings, including verbatim clauses and the questions that remain unanswered, are in the 2026-08-05 provider-terms bulletin.
Read the caveats below in context: FernWX today is a strictly personal, research-oriented deployment — no revenue, no advertising, no users beyond its operator. Nearly every restriction found is written to bind commercial use, and three providers carve personal use out by name. Attribution is the exception — Tomorrow.io requires it on every tier, Open-Meteo’s CC BY 4.0 applies to both tiers, and upgrading to a paid plan removes the non-commercial restriction, not the credit. The obligations on this page therefore apply now; most of the caveats begin to bite on the day FernWX charges anyone, advertises, or admits a second real user.
- Synoptic Data: the tier-specific CWOP/station-network attribution obligation isn’t fully documented in public terms. Verify this section against FernWX’s actual signed commercial license before treating it as final.
- Tomorrow.io: their public terms restrict storing “unaltered Datafeed” without an Order that explicitly permits it, and §1.5 prohibits commercial use on self-generated accounts specifically. FernWX’s Weather Ledger stores raw Tomorrow.io payloads long-term under the forecast-memory invariant — that is consistent with non-commercial personal use today, but confirm the actual Order covers it before commercializing, or negotiate an amendment.
- Copernicus/CAMS citation: corrected 2026-08-05. This page previously prescribed the Copernicus Climate Change Service (C3S) citation; the air-quality data comes from CAMS, the Copernicus Atmosphere Monitoring Service, which takes a different one. The full CAMS form also carries a year stamp — decide whether to hardcode it, template it at render time, or keep it static, because it will go stale otherwise.
- WeatherAPI.com caching cap: their terms permit unrestricted retention of historical data but cap forecast caching at 24 hours. Retaining forecasts specifically so they can be scored against later observations is the core FernWX behavior and sits in tension with that figure. No clause resolves whether “cache for performance optimisation” governs archival for a different purpose.
- The Weather Company: no public document governs evaluation entitlement ENT0011896, so whether data collected during the trial may be retained after it expires cannot be determined from public terms. Get this in writing before relying on the archive — and establish first whether IBM or Francisco Partners, who acquired the business in February 2024, is the party to ask.
- Derived-data ownership is unaddressed everywhere it was asked — WeatherAPI, Visual Crossing, and Open-Meteo are all silent on who owns a forecast-accuracy score computed from a provider’s forecast and a third party’s observation. That score is FernWX’s core output.
- Legal review: none of the terms summarized here have been reviewed by counsel. Commercializing FernWX changes how several of these terms apply simultaneously (Tomorrow.io, Open-Meteo, and Visual Crossing all flip on the same event) — get legal sign-off before charging users.
- No staleness check exists: provider ToS pages can change without notice and nothing in FernWX re-verifies them. This page predicted that about itself on 2026-07-06 and then went stale in one month, as six new sources were added without being listed here. Treat every clause as last-verified-2026-08-05, not as currently-true, and re-run the research rather than trusting this page indefinitely.