FernWX Knowledge Base

How FernWX works, and what every part of it can do.

FernWX is an auditability-first weather platform: it collects from many providers, preserves every forecast as immutable memory, and keeps the evidence trail visible. This page is the map — the pipeline behind the platform, then each feature and the questions it answers.

Open Forecast Explore Forecast Memory

How FernWX works

Collect, preserve, present

Most weather apps show you one blended answer and discard yesterday's. FernWX is built the other way around: the record comes first, and every surface is a view over it.

1 · Collect

Dedicated collectors fetch forecasts, observations, alerts, text products, and measurements from each provider on a fixed cadence, independently of anyone visiting the site.

2 · Preserve

Everything lands in the Weather Ledger with normalized history and the raw provider payload kept as evidence. Forecast runs are immutable: a new run is added beside the old one, never over it.

3 · Present

The web app and native clients are read-only consumers of the ledger. They never call providers directly, so what you see is always the recorded evidence, not a fresh unrecorded fetch.

The core invariant

Forecast memory is immutable. Old forecast runs are never overwritten, so questions that are unanswerable elsewhere stay answerable here: which provider changed first, which stayed stable, and which ended up closest to what was observed. AI features can summarize and explain that record, but they never write to it — the line between source data and interpretation is kept visible everywhere.

Live present and future

Weather

The operational surfaces: what is happening at your locations right now, what each provider says comes next, and the official context around both.

Forecast

Now & Next conditions for each of your locations, with every provider shown side by side. FernWX ranks providers and shows the basis for the ranking instead of silently blending them into one number.

Answers: What is the forecast, which sources agree, and why is one ranked first?

Open Forecast

Severe & Alerts

Active NWS alerts, SPC convective outlooks, a storm archive, and nearby upper-air context for your tracked locations. Qualifying severe weather automatically activates Storm Mode collection.

Answers: Is anything active near me, and what did past events look like?

Open Severe & Alerts

Discussions

Area Forecast Discussions — the forecaster-written reasoning behind NWS forecasts — collected and kept alongside the data they explain.

Answers: What are human forecasters actually thinking about this setup?

Open Discussions

Measurements

Radiosonde (weather balloon) measurements from the launch sites that matter for your locations: the observed vertical profile of the real atmosphere, not a model of it.

Answers: What did the atmosphere actually look like above the nearest launch site?

Open Measurements

Maps

Map views of conditions and context around your tracked locations.

Open Maps

The auditability differentiator

Memory

Forecast memory is the core FernWX primitive: every forecast run is preserved and never overwritten. The Memory workspace is where you look backward — its four tabs share one location and query state, so a question carries across them.

Replay

Scrub back to any earlier moment and see the forecast exactly as it stood then — which provider changed first, and which stayed stable as the event approached.

Answers: What did the forecast say on Tuesday about Friday?

Open Replay

Verification

Forecasts scored against what was later observed, so provider performance is measured rather than remembered.

Answers: Who was actually right, and by how much?

Open Verification

Providers

One card per provider: its temperature rank and mean absolute error against the NWS station reference with the sample count behind it, alongside the attribution, cadence, and interpretation limits that qualify how to read that rank.

Answers: Who is ahead, and what caveat governs that claim?

Open Providers

Records

The persisted forecast and verification rows behind Memory comparisons, with retrieval times, valid times, references, signed and absolute error, filters by provider, variable, knowledge lead, and valid-time range, and a JSON or CSV export of the whole filtered set.

Answers: Where did this value come from, and when was it collected?

Open Records

Query and analyze the record

Intelligence

Analytical surfaces built on top of the ledger. AI has a bounded role here: it can query, summarize, and explain the record, but it never writes weather truth and its output is always labeled as interpretation.

Smart Card Library

Saved, re-runnable analysis cards. Cards can be saved straight from report sections, stay pinned to the location scope they were created under, re-run on current data, and export as presentation-ready PNGs with run provenance stamped on them.

Open Smart Card Library

Observatory

Curated analytical dashboards over the ledger: provider trust scores, forecast volatility, lead-time skill, nowcast-versus-reality, and data freshness — the standing questions, pre-built.

Open Observatory

Research Lab

Ask questions of your ledger in plain language. FernWX translates them to SQL over your account-scoped data, shows the query it ran, and charts the result — the question surface for anything the Observatory does not already answer.

Answers: Ad-hoc questions like: how did overnight low forecasts drift last month?

Open Research Lab

Reports

Agentic multi-step reports: an agent plans a sequence of queries against your ledger, runs them, and assembles the findings into a structured report whose sections can be saved to the Smart Card Library.

Open Reports

Storm Mode and collections

FernWX collects differently when severe weather matters.

FernWX normally collects weather on its standard cadence so the platform can preserve forecast history, observations, and the context around changing conditions without overwhelming the ledger.

When severe weather reaches the threshold FernWX cares about, Storm Mode turns on automatically. That switches the platform into a Rapid collection mode so warning periods are preserved with tighter timing and better event context.

Storm Mode is about evidence. It helps answer questions like what warning was active, what nearby upper-air profile was available, what the forecast outlook looked like, and what the weather sources were saying while the event was unfolding.

Normal collection

Used for day-to-day forecast memory, provider comparison, and account weather history.

Storm Mode

Used during qualifying severe-weather periods so FernWX can preserve the warning, the nearby environment, and the faster-changing source data together.

Why this exists

FernWX is built for people who want to inspect what happened, not just glance at a single weather value and move on.

Where the data comes from

Data sources

Every location you add is collected from all applicable providers by default — you never have to pick sources to get full coverage, and you can opt individual ones out per account.

Apple WeatherKit — Forecasts and current conditions
National Weather Service — Forecasts, alerts, discussions, radiosonde and SPC products
Open-Meteo — Forecasts, historical context, and air quality
Tomorrow.io — Forecasts and current conditions
NOAA MADIS — Account-selected CWOP / Integrated Mesonet surface stations
USGS — Optional hydrology data

See the full list of data sources and their attribution requirements.

Accounts and keys

Accounts, invites, and BYOK

FernWX is currently invite-only. An account carries your tracked locations, preferences, and account-scoped ledger history; signed-out visitors get a public forecast lookup that never touches account data.

Bring your own key. AI features can run on your own OpenRouter key (and an OpenAI key for speech) instead of the operator's. Stored keys are encrypted, never shown back to any client after saving, and never echoed into error messages.

For agents and scripts

The Agent API

Everything the app can read, an authorized agent can read too. The Agent API exposes the ledger through an OpenAPI contract with account-scoped, expiring API keys, so your own tools and AI agents can query the same record this site renders.

Open the interactive API reference