Heads up for anyone using the Swedish SMHI weather provider in MagicMirror²!
As of March 31, 2026, SMHI has deprecated their PMP3gv2 forecast API. It now returns HTTP 404.
I noticed this, this week when my MM suddenly were empty of weather reports.
The replacement is SNOW1gv1, hosted on the same domain but with a different data structure.
What changed in the API
- URL path:
pmp3g/version/2 → snow1g/version/1
- Time key:
validTime → time
- Data structure: The nested
parameters[] array is replaced by a flat data object (e.g. entry.data.air_temperature instead of entry.parameters.find(p => p.name === 't').values[0])
- Parameter names: Short codes replaced by human-readable names (
t → air_temperature, ws → wind_speed, Wsymb2 → symbol_code, etc.)
- Coordinates: Response now returns flat
[lon, lat] instead of nested [[lon, lat]]
approvedtime.json endpoint: Removed entirely — use referenceTime from the data response instead
Weather symbol codes (1–27) remain unchanged, so icon mapping still works as before.
Updated provider
I’ve updated the smhi.js provider to work with SNOW1gv1. Key changes:
- New API URL
- Rewritten data parser for the flat
data object structure
- All parameter names mapped to their new equivalents
- Coordinate parsing updated for the new format
- Added missing value handling (SMHI uses
9999 as sentinel)
- Added support for precipitation type
11 (drizzle, new in SNOW1gv1)
- Backward compatible — existing
config.js settings (including precipitationValue) work without changes
Tested and confirmed working with type: "daily" on a Raspberry Pi. The SNOW1gv1 API responds correctly and the weather module displays data as expected.
Code:
const Log = require("logger");
const { getSunTimes, isDayTime, validateCoordinates } = require("../provider-utils");
const HTTPFetcher = require("#http_fetcher");
/**
* Server-side weather provider for SMHI (Swedish Meteorological and Hydrological Institute)
* Sweden only, metric system
*
* API: SNOW1gv1 — https://opendata.smhi.se/metfcst/snow1gv1
* Migrated from PMP3gv2 (deprecated 2026-03-31, returns HTTP 404)
*
* Version: 2.0.1 (2026-04-02)
*
* Key differences from PMP3gv2:
* - URL: snow1g/version/1 (was pmp3g/version/2)
* - Time key: "time" (was "validTime")
* - Data structure: flat object entry.data.X (was parameters[].find().values[0])
* - Parameter names: human-readable (air_temperature, wind_speed, etc.)
* - Coordinates: flat [lon, lat] (was nested [[lon, lat]])
* - Precipitation types: different value mapping (1=rain, not snow)
*/
/**
* Maps user-facing config precipitationValue to SNOW1gv1 parameter names.
* Maintains backward compatibility with existing MagicMirror configs.
*/
const PRECIP_VALUE_MAP = {
pmin: "precipitation_amount_min",
pmean: "precipitation_amount_mean",
pmedian: "precipitation_amount_median",
pmax: "precipitation_amount_max"
};
class SMHIProvider {
constructor (config) {
this.config = {
lat: 0,
lon: 0,
precipitationValue: "pmedian", // pmin, pmean, pmedian, pmax
type: "current",
updateInterval: 5 * 60 * 1000,
...config
};
// Validate precipitationValue
if (!Object.keys(PRECIP_VALUE_MAP).includes(this.config.precipitationValue)) {
Log.warn(`[smhi] Invalid precipitationValue: ${this.config.precipitationValue}, using pmedian`);
this.config.precipitationValue = "pmedian";
}
this.fetcher = null;
this.onDataCallback = null;
this.onErrorCallback = null;
}
initialize () {
try {
// SMHI requires max 6 decimal places
validateCoordinates(this.config, 6);
this.#initializeFetcher();
} catch (error) {
Log.error("[smhi] Initialization failed:", error);
if (this.onErrorCallback) {
this.onErrorCallback({
message: error.message,
translationKey: "MODULE_ERROR_UNSPECIFIED"
});
}
}
}
setCallbacks (onData, onError) {
this.onDataCallback = onData;
this.onErrorCallback = onError;
}
start () {
if (this.fetcher) {
this.fetcher.startPeriodicFetch();
}
}
stop () {
if (this.fetcher) {
this.fetcher.clearTimer();
}
}
#initializeFetcher () {
const url = this.#getUrl();
this.fetcher = new HTTPFetcher(url, {
reloadInterval: this.config.updateInterval,
logContext: "weatherprovider.smhi"
});
this.fetcher.on("response", async (response) => {
try {
const data = await response.json();
this.#handleResponse(data);
} catch (error) {
Log.error("[smhi] Failed to parse JSON:", error);
if (this.onErrorCallback) {
this.onErrorCallback({
message: "Failed to parse API response",
translationKey: "MODULE_ERROR_UNSPECIFIED"
});
}
}
});
this.fetcher.on("error", (errorInfo) => {
if (this.onErrorCallback) {
this.onErrorCallback(errorInfo);
}
});
}
#handleResponse (data) {
try {
if (!data.timeSeries || !Array.isArray(data.timeSeries)) {
throw new Error("Invalid weather data");
}
const coordinates = this.#resolveCoordinates(data);
let weatherData;
switch (this.config.type) {
case "current":
weatherData = this.#generateCurrentWeather(data.timeSeries, coordinates);
break;
case "forecast":
case "daily":
weatherData = this.#generateForecast(data.timeSeries, coordinates);
break;
case "hourly":
weatherData = this.#generateHourly(data.timeSeries, coordinates);
break;
default:
Log.error(`[smhi] Unknown weather type: ${this.config.type}`);
if (this.onErrorCallback) {
this.onErrorCallback({
message: `Unknown weather type: ${this.config.type}`,
translationKey: "MODULE_ERROR_UNSPECIFIED"
});
}
return;
}
if (this.onDataCallback) {
this.onDataCallback(weatherData);
}
} catch (error) {
Log.error("[smhi] Error processing weather data:", error);
if (this.onErrorCallback) {
this.onErrorCallback({
message: error.message,
translationKey: "MODULE_ERROR_UNSPECIFIED"
});
}
}
}
#generateCurrentWeather (timeSeries, coordinates) {
const closest = this.#getClosestToCurrentTime(timeSeries);
return this.#convertWeatherDataToObject(closest, coordinates);
}
#generateForecast (timeSeries, coordinates) {
const filled = this.#fillInGaps(timeSeries);
return this.#convertWeatherDataGroupedBy(filled, coordinates, "day");
}
#generateHourly (timeSeries, coordinates) {
const filled = this.#fillInGaps(timeSeries);
return this.#convertWeatherDataGroupedBy(filled, coordinates, "hour");
}
/**
* Find the time series entry closest to the current time.
* SNOW1gv1 uses "time" instead of PMP3gv2's "validTime".
*/
#getClosestToCurrentTime (times) {
const now = new Date();
let minDiff = null;
let closest = times[0];
for (const time of times) {
const entryTime = new Date(time.time);
const diff = Math.abs(entryTime - now);
if (minDiff === null || diff < minDiff) {
minDiff = diff;
closest = time;
}
}
return closest;
}
/**
* Convert a single SNOW1gv1 time series entry to MagicMirror weather object.
*
* SNOW1gv1 data structure: entry.data.parameter_name (flat object)
* PMP3gv2 used: entry.parameters[{name, values}] (array of objects)
*/
#convertWeatherDataToObject (weatherData, coordinates) {
const date = new Date(weatherData.time);
const { sunrise, sunset } = getSunTimes(date, coordinates.lat, coordinates.lon);
const isDay = isDayTime(date, sunrise, sunset);
const current = {
date: date,
humidity: this.#paramValue(weatherData, "relative_humidity"),
temperature: this.#paramValue(weatherData, "air_temperature"),
windSpeed: this.#paramValue(weatherData, "wind_speed"),
windFromDirection: this.#paramValue(weatherData, "wind_from_direction"),
weatherType: this.#convertWeatherType(this.#paramValue(weatherData, "symbol_code"), isDay),
feelsLikeTemp: this.#calculateApparentTemperature(weatherData),
sunrise: sunrise,
sunset: sunset,
snow: 0,
rain: 0,
precipitationAmount: 0
};
// Map user config (pmedian/pmean/pmin/pmax) to SNOW1gv1 parameter name
const precipParamName = PRECIP_VALUE_MAP[this.config.precipitationValue];
const precipitationValue = this.#paramValue(weatherData, precipParamName);
const pcat = this.#paramValue(weatherData, "predominant_precipitation_type_at_surface");
// SNOW1gv1 precipitation type mapping (differs from PMP3gv2!):
// 0 = no precipitation
// 1 = rain
// 2 = sleet (snow + rain mix)
// 5 = snow / freezing rain
// 6 = freezing mixed precipitation
// 11 = drizzle / light rain
switch (pcat) {
case 1: // Rain
case 11: // Drizzle / light rain
current.rain = precipitationValue;
current.precipitationAmount = precipitationValue;
break;
case 2: // Sleet / mixed rain and snow
current.snow = precipitationValue / 2;
current.rain = precipitationValue / 2;
current.precipitationAmount = precipitationValue;
break;
case 5: // Snow / freezing rain
case 6: // Freezing mixed precipitation
current.snow = precipitationValue;
current.precipitationAmount = precipitationValue;
break;
case 0:
default:
break;
}
return current;
}
#convertWeatherDataGroupedBy (allWeatherData, coordinates, groupBy = "day") {
const result = [];
let currentWeather = null;
let dayWeatherTypes = [];
const allWeatherObjects = allWeatherData.map((data) => this.#convertWeatherDataToObject(data, coordinates));
for (const weatherObject of allWeatherObjects) {
const objDate = new Date(weatherObject.date);
// Check if we need a new group (day or hour change)
const needNewGroup = !currentWeather || !this.#isSamePeriod(currentWeather.date, objDate, groupBy);
if (needNewGroup) {
currentWeather = {
date: objDate,
temperature: weatherObject.temperature,
minTemperature: Infinity,
maxTemperature: -Infinity,
snow: 0,
rain: 0,
precipitationAmount: 0,
sunrise: weatherObject.sunrise,
sunset: weatherObject.sunset
};
dayWeatherTypes = [];
result.push(currentWeather);
}
// Track weather types during daytime
const { sunrise: daySunrise, sunset: daySunset } = getSunTimes(objDate, coordinates.lat, coordinates.lon);
const isDay = isDayTime(objDate, daySunrise, daySunset);
if (isDay) {
dayWeatherTypes.push(weatherObject.weatherType);
}
// Use median weather type from daytime hours
if (dayWeatherTypes.length > 0) {
currentWeather.weatherType = dayWeatherTypes[Math.floor(dayWeatherTypes.length / 2)];
} else {
currentWeather.weatherType = weatherObject.weatherType;
}
// Aggregate min/max and precipitation
currentWeather.minTemperature = Math.min(currentWeather.minTemperature, weatherObject.temperature);
currentWeather.maxTemperature = Math.max(currentWeather.maxTemperature, weatherObject.temperature);
currentWeather.snow += weatherObject.snow;
currentWeather.rain += weatherObject.rain;
currentWeather.precipitationAmount += weatherObject.precipitationAmount;
}
return result;
}
#isSamePeriod (date1, date2, groupBy) {
if (groupBy === "hour") {
return date1.getFullYear() === date2.getFullYear()
&& date1.getMonth() === date2.getMonth()
&& date1.getDate() === date2.getDate()
&& date1.getHours() === date2.getHours();
} else { // day
return date1.getFullYear() === date2.getFullYear()
&& date1.getMonth() === date2.getMonth()
&& date1.getDate() === date2.getDate();
}
}
/**
* Fill gaps in time series data for forecast/hourly grouping.
* SNOW1gv1 has variable time steps: 1h (0-48h), 2h (49-72h), 6h (73-132h), 12h (133h+).
* Uses "time" key instead of PMP3gv2's "validTime".
*/
#fillInGaps (data) {
if (data.length === 0) return [];
const result = [];
result.push(data[0]);
for (let i = 1; i < data.length; i++) {
const from = new Date(data[i - 1].time);
const to = new Date(data[i].time);
const hours = Math.floor((to - from) / (1000 * 60 * 60));
// Fill gaps with previous data point (start at j=1 since j=0 is already pushed)
for (let j = 1; j < hours; j++) {
const current = { ...data[i - 1] };
const newTime = new Date(from);
newTime.setHours(from.getHours() + j);
current.time = newTime.toISOString();
result.push(current);
}
// Push original data point
result.push(data[i]);
}
return result;
}
/**
* Extract coordinates from SNOW1gv1 response.
* SNOW1gv1 returns flat GeoJSON Point: { coordinates: [lon, lat] }
* PMP3gv2 returned nested: { coordinates: [[lon, lat]] }
*/
#resolveCoordinates (data) {
const coords = data?.geometry?.coordinates;
if (Array.isArray(coords) && coords.length >= 2 && typeof coords[0] === "number") {
// SNOW1gv1 flat format: [lon, lat]
return {
lat: coords[1],
lon: coords[0]
};
}
Log.warn("[smhi] Invalid coordinate structure in response, using config values");
return {
lat: this.config.lat,
lon: this.config.lon
};
}
/**
* Calculate apparent (feels-like) temperature using humidity and wind.
* Uses SNOW1gv1 parameter names.
*/
#calculateApparentTemperature (weatherData) {
const Ta = this.#paramValue(weatherData, "air_temperature");
const rh = this.#paramValue(weatherData, "relative_humidity");
const ws = this.#paramValue(weatherData, "wind_speed");
if (Ta === null || rh === null || ws === null) {
return Ta; // Fallback to raw temperature if data missing
}
const p = (rh / 100) * 6.105 * Math.exp((17.27 * Ta) / (237.7 + Ta));
return Ta + 0.33 * p - 0.7 * ws - 4;
}
/**
* Get parameter value from SNOW1gv1 flat data structure.
* SNOW1gv1: weatherData.data.parameter_name (direct property access)
* PMP3gv2 used: weatherData.parameters.find(p => p.name === name).values[0]
*
* Returns null if parameter missing or equals SMHI missing value (9999).
*/
#paramValue (weatherData, name) {
const value = weatherData.data?.[name];
if (value === undefined || value === null) {
return null;
}
// SMHI uses 9999 as missing value sentinel for all parameters
if (value === 9999) {
return null;
}
return value;
}
/**
* Convert SMHI symbol_code (1-27) to MagicMirror weather icon names.
* Symbol codes are identical between PMP3gv2 and SNOW1gv1.
*/
#convertWeatherType (input, isDayTime) {
switch (input) {
case 1:
return isDayTime ? "day-sunny" : "night-clear"; // Clear sky
case 2:
return isDayTime ? "day-sunny-overcast" : "night-partly-cloudy"; // Nearly clear sky
case 3:
case 4:
return isDayTime ? "day-cloudy" : "night-cloudy"; // Variable/halfclear cloudiness
case 5:
case 6:
return "cloudy"; // Cloudy/overcast
case 7:
return "fog";
case 8:
case 9:
case 10:
return "showers"; // Light/moderate/heavy rain showers
case 11:
case 21:
return "thunderstorm";
case 12:
case 13:
case 14:
case 22:
case 23:
case 24:
return "sleet"; // Light/moderate/heavy sleet (showers)
case 15:
case 16:
case 17:
case 25:
case 26:
case 27:
return "snow"; // Light/moderate/heavy snow (showers/fall)
case 18:
case 19:
case 20:
return "rain"; // Light/moderate/heavy rain
default:
return null;
}
}
/**
* Build SNOW1gv1 forecast URL.
* Changed from: pmp3g/version/2
* Changed to: snow1g/version/1
*/
#getUrl () {
const lon = this.config.lon.toFixed(6);
const lat = this.config.lat.toFixed(6);
return `https://opendata-download-metfcst.smhi.se/api/category/snow1g/version/1/geotype/point/lon/${lon}/lat/${lat}/data.json`;
}
}
module.exports = SMHIProvider;
