SHMÚ Weather Forecast for Slovakia (ALADIN)

Will it rain at your place today, tomorrow or the day after? This Actor reads the official forecast of the Slovak Hydrometeorological Institute (SHMÚ) from its high-resolution ALADIN model and returns one simple row per day: rain yes/no, how many millimetres, at what time, plus temperature, wind gusts and clouds.

Use it for a cottage, a hike, a garden, an event, or as a daily weather feed for your own automation (Make, Zapier, n8n, a webhook).

What you get

• ☔ Rain yes/no for each day, using a threshold you choose
• 🕒 When it rains, for example 14:00–17:00, in Slovak time
• ❄️ Snow or rain: total precipitation, how much of it is snow, and the type (rain, snow, mixed)
• 🌡️ Min/max temperature, strongest wind gusts (km/h) and average cloud cover
• ⏱️ Optional hour-by-hour forecast
• 📍 About 1,000 places in Slovakia. Use a town name, an SHMÚ ID, or GPS coordinates; the nearest SHMÚ forecast point is picked automatically.

Input

Field	Description	Default
locations	Towns or villages (Prešov, presov), GPS coordinates (49.05, 21.30), or SHMÚ IDs (31379)	["Prešov"]
days	1–3: today, tomorrow, the day after	3
rainThresholdMm	A day counts as rainy when its total rain and snow is at least this many mm	0.5
includeHourly	Add an hourly list to each day	false
proxyConfiguration	shmu.sk closes connections from cloud servers, so Apify Proxy is on by default (the datacenter proxy is enough)	Apify Proxy

{
    "locations": ["Prešov", "49.05, 21.30", "Štrbské Pleso"],
    "days": 3,
    "rainThresholdMm": 0.5
}

If a name has several SHMÚ points (for example Košice (centrum) and Košice (letisko)), the town centre is used, and the run log lists the other IDs. If a name isn't found, the log suggests similar names.

Output

One item per location and day:

{
    "location": "Prešov",
    "query": "Prešov",
    "stationId": 31379,
    "latitude": 49,
    "longitude": 21.25,
    "elevationM": 295,
    "date": "2026-10-16",
    "day": "tomorrow",
    "willRain": true,
    "precipitationMm": 3.2,
    "snowMm": 0,
    "precipitationType": "rain",
    "rainyHours": 4,
    "rainTimes": "14:00–18:00",
    "maxHourlyPrecipitationMm": 1.4,
    "temperatureMinC": 3.6,
    "temperatureMaxC": 12.9,
    "maxWindGustKmh": 27,
    "cloudCoverPercent": 74,
    "fromTime": "2026-10-16T00:00+02:00",
    "toTime": "2026-10-17T00:00+02:00",
    "model": "ALADIN SHMU/SK 4.5km 87L",
    "modelRun": "2026-10-15T00:00Z",
    "sourceUrl": "https://www.shmu.sk/data/datanwp/json/aladin/2026-10-15/31379_2026-10-15_00.json"
}

The run's status message also gives a one-line answer, for example Prešov: today dry, tomorrow rain 3.2 mm (14:00–18:00), day after tomorrow dry.

How "rain" is decided

• ALADIN gives precipitation for every hour. An hour with at least 0.1 mm counts as rainy and shows up in rainTimes.
• A day gets willRain: true when its total is at least rainThresholdMm (0.5 mm by default, which is about a light shower).
• For today, only the hours that haven't happened yet are counted (see fromTime).
• Snow is counted as its water equivalent, so 1 mm is roughly 1 cm of fresh snow.
• precipitationType describes what falls (rain, snow, mixed) even when it's below the threshold. It's none only for less than 0.1 mm in the day.

Data source

Forecast data comes from the Slovak Hydrometeorological Institute (SHMÚ), shmu.sk, model ALADIN SHMU/SK (4.5 km grid, updated 4 times a day). This Actor is not affiliated with SHMÚ.

The Actor uses the newest model run that reaches the end of the last requested day. The 00 UTC run looks 4 days ahead, but the 06, 12 and 18 UTC runs only look 3 days ahead. So at night, a 3-day request uses the previous 00 UTC run. The modelRun field shows which run was used.

The Actor uses the same JSON endpoints as the interactive meteograms on shmu.sk. These aren't a documented public API, so they may change without notice.

Limitations

• Slovakia only: GPS points more than 30 km from the nearest SHMÚ point are rejected.
• GPS input uses the nearest SHMÚ point. In the mountains, that can be a peak or a mountain hut (e.g. Chopok), which has very different weather from the valley. Check location and elevationM in the output, and if needed enter a nearby village by name.
• ALADIN looks about 3–4 days ahead, so this Actor returns at most 3 days.
• A forecast point stands for a 4.5 km grid area. In the mountains, the real weather can differ from the forecast.
• shmu.sk doesn't accept connections straight from cloud servers. Keep Apify Proxy turned on when you run this on Apify.

Development

npm install
npm start          # runs locally with input from storage/key_value_stores/default/INPUT.json
npm test           # unit tests (vitest)
npm run build      # TypeScript type-check and compile

npm i -g apify-cli
apify login
apify push         # build and deploy to your Apify account

The code is split into small steps that are easy to follow:

File	What it does
src/main.ts	Reads input, runs an HttpCrawler, writes the status message
src/routes.ts	3 crawler steps: location list → forecast files for a location → forecast
src/stations.ts	Matches a name, ID or GPS point to an SHMÚ forecast point
src/forecast.ts	Turns hourly ALADIN data into one summary per day (in Slovak time)