Weather

Overview

The Weather widget (registry id weather, built by WeatherStrip) shows the most recent weather reading as of the playhead as a row of stat tiles. Reach for it to check conditions at a given point in the session, for example whether rain arrived before a round of pit stops.

The store keeps the session’s whole weather history, so scrubbing the playhead backwards shows the reading that was current at that moment, not an empty strip. For the shape of a change over time, use the four Weather Charts.

What It Shows

The Weather strip mid-session; fields missing at source render as dashes (Madrid 2026)

Tile	Field	Format
Air	`air_temp`	Degrees Celsius, 1 decimal place
Track	`track_temp`	Degrees Celsius, 1 decimal place
Wind	`wind_speed` (with `wind_direction` when known)	m/s, with degrees appended when direction is available
Humidity	`humidity`	Per cent, whole number
Rain	`rainfall`	A 0 or 1 flag, whole number

Any field that is missing or not a finite number renders its tile as a dash, never a fabricated zero.

Data Behind It

Weather is entirely client-derived, with no insight metric behind it.

WS channel: weather, part of the Section 5 envelope family (vpw:v1:{session_key}:weather) defined in libs/vpw-contracts.
REST hydration: GET /v1/sessions/{session_key}/weather, an offset-paged row endpoint, read by SessionController.enter alongside the other row endpoints and re-read on a WS reconnect or a seek.
A retained history, not a single slot. Every envelope is appended to the session’s weather history. The weatherHistoryAsOf selector filters that history by the playhead cutoff, and weatherAsOf picks the latest surviving reading for this strip. The four chart widgets read the same filtered history.
Column names: the weather table’s real columns are the short forms air_temp and track_temp, not the longer air_temperature and track_temperature.
Live and replay envelopes are wire-identical; the widget never branches on envelope source.

States

State	Behaviour
No reading received yet	”No weather data” empty state
Playhead scrubbed before the session’s first reading	Same empty state: nothing is yet “as of” the cutoff
Playhead scrubbed back mid-session	Shows the reading that was current then, not the session’s last one
Live vs replay	Identical rendering
Session-type gating	None: shown in every session type
Reading present but some fields missing or non-numeric	Only the affected tiles show a dash; the rest render normally

FAQ

Why are Air and Track blank on some backfilled sessions?

FastF1-backfilled weather rows can carry no temperature values at all. The tiles show dashes rather than inventing a figure. The live-sourced copy of the same session usually has them.

Does this update while the playhead moves?

Yes. The strip always shows the latest reading at or before the playhead, so it changes as you scrub.

What does Rain = 1 mean?

The feed reports rainfall as an on or off flag rather than a rate, so 1 means wet and 0 means dry. There is no millimetre figure on the wire.

Next Steps

Weather Charts

The same readings plotted across the whole session.

Race Control

Official messages issued as conditions changed.

Timing Tower

How the field responded to the conditions.

Stints

Tyre choices against the weather at the time.

Internal Tools

Third-Party Tools

Developer Docs

Overview

What It Shows

Data Behind It

States

FAQ

Next Steps

Weather Charts

Race Control

Timing Tower

Stints

​Overview

​What It Shows

​Data Behind It

​States

​FAQ

​Next Steps

Weather Charts

Race Control

Timing Tower

Stints

Overview

What It Shows

Data Behind It

States

FAQ

Next Steps