Open-Meteo Integration Notes

Purpose

This document describes the Open-Meteo API usage currently implemented by weatherfeeder. It is for developers and operators maintaining Open-Meteo source URLs, normalizers, fixtures, and tests.

General config syntax belongs in configuration. Emitted JSON events are documented in event wire contract.

Implemented Drivers

Driver	Kind	Raw schema	Canonical schema
`openmeteo_observation`	`observation`	`raw.openmeteo.current.v1`	`weather.observation.v1`
`openmeteo_forecast`	`forecast`	`raw.openmeteo.hourly.forecast.v1`	`weather.forecast.v1`

Config Requirements

Both drivers require HTTP source params:

url
user_agent

The shared HTTP helper also accepts conditional, http_timeout, and http_response_body_limit_bytes. Conditional requests are enabled by default; an upstream 304 Not Modified response emits no event for that poll.

Upstream Shapes Used

openmeteo_observation expects a JSON response with top-level location/timezone metadata and a current object. The normalizer uses:

latitude, longitude, timezone, utc_offset_seconds;
current.time;
current temperature, apparent temperature, relative humidity, weather code, wind speed/direction/gusts, pressure, and is_day.

openmeteo_forecast expects top-level location/timezone metadata and an array-oriented hourly object. The normalizer uses:

hourly.time;
hourly temperature, apparent temperature, dew point, relative humidity, precipitation probability, precipitation amount, snowfall, weather code, pressure, wind speed/direction/gusts, is_day, cloud cover, visibility, and UV index.

Open-Meteo field presence is allowed to vary. Missing optional arrays produce nil canonical fields for the affected periods.

Accept Header

Open-Meteo sources request:

application/json

Time Handling

Open-Meteo timestamps often omit an explicit offset. The provider helper parses times by using the returned timezone or utc_offset_seconds when needed.

Observation source events set effective_at from current.time when it can be parsed. Hourly forecast source events prefer current.time, then the first non-empty hourly.time entry.

The hourly forecast normalizer sets canonical issuedAt from the incoming event emitted_at when present, otherwise from the first hourly period start. Normalized forecast effective_at matches issuedAt.

Mapping Notes

Open-Meteo is not a station feed. Weatherfeeder synthesizes canonical station/location IDs from latitude and longitude when both are available.

Open-Meteo weather codes are WMO codes and are treated as authoritative. Canonical text is derived from the WMO code and day/night hint.

Wind speed and gust fields are treated as kilometers per hour. Pressure values are treated as hPa and converted to Pa. Snowfall values are treated as centimeters and converted to millimeters.

Hourly forecast period end time is the next period start. The last period uses the previous interval length, or one hour when there is no previous interval.

Failure Behavior

Constructor validation failures stop daemon startup. Polling failures are returned to the scheduler. Metadata decoding failures in sources still allow raw payload emission when the HTTP response itself succeeded.

Normalization fails when required time data is missing or invalid, such as an empty hourly.time array for hourly forecasts.

Tests To Inspect

internal/sources/openmeteo/source_test.go
internal/normalizers/openmeteo/*_test.go
internal/providers/openmeteo/*_test.go

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