How long is the shortest day in Vienna?

On 21 December 2026 the sun rises in Vienna at 7:43 and sets at 16:03 — 8 h 20 min of daylight. On 21 June it is 16 h 4 min.

How high does the sun get in Vienna in winter?

At noon on 21 December, 18.4° above the horizon; on 21 June, 65.2°. At 18.4° a 21-metre building casts a shadow of about 63 metres — in June about 10 metres.

Does a ground-floor flat in Vienna get sun in winter?

In dense Gründerzeit lanes often hardly any. In a 15-metre-wide east–west lane between 21-metre buildings, the shadow edge on the facade opposite sits at about 16 metres at noon on 21 December; everything below stays in the shade of the building across. For a specific flat it depends on floor, side and the neighbours’ heights — Azima calculates that room by room.

Where in Vienna is there the most winter sun?

Measured at street level at the centre of each Grätzl on 21 December: most in Cottageviertel (8.0 h), Hirschstetten (8.0 h), Leopoldau (8.0 h); least in Burggasse (0.2 h), Keplerplatz (0.2 h), Währing Zentrum (0.3 h). A single flat depends on floor, orientation and courtyard side.

Dollhouse view of the example flat at Schrankgasse 10 on 21 June at 15:00: sunlight falls into the living room

The same view on 21 December at 15:00: the flat lies in the shadow of the neighbouring buildings

21 June · 15:0021 December · 15:00

A flat in Vienna-Neubau · second floor

Viewed in June. Lived in December.

Q: How does Azima calculate the sun inside a flat?

Azima builds the house and its neighbours from the City of Vienna’s roof model as a 3D world in the browser and runs the sun over it — on the graphics card of your phone or laptop, without a server. The address goes to OpenStreetMap only for the neighbouring buildings; the floor plan never leaves the device. It calculates a clear sky — against high fog, even the fourth floor does not help.

On 21 December the sun rises over Vienna at 7:43 and sets at 16:03: 8 h 20 min of daylight. At noon it stands 18.4° high — on 21 June it is 65.2°. What that means for a real flat is shown below, quarter hour by quarter hour, from the Azima stage: the house at Schrankgasse 10 with its measured neighbours.

The flat at Schrankgasse 10 on 21 December at noon, seen from above

7:43 · Sunrise.The bedroom won’t see it until 9:10.
20 minutes of sun in the bedroom.9:10 to 9:30, through the courtyard window. That is all this room gets today.
11:35 · Now the living room.Street side, facing west: 3 h 5 min of sun, until 14:40.
Noon. It climbs no higher than 18.4°.On 21 June, at the same hour, it stands at 65.2°.
The living room keeps it until 14:40.The same flat, the same day — one room has three hours, the other twenty minutes.
15:00 — the same minute as in June above.This time the sun stands 7.0° above the horizon.
16:03 · Sunset.8 h 20 min of daylight. In June it is 16 h 4 min.
17:30 · Night.In June it would stay light for another 3 h 29 min.

Why Vienna is like this

8 h 20 min of light.

In June it is almost twice as long, and at noon the sun stands more than three times as high.

Astronomical sun path for Vienna, 48.2° N

Vienna sits where the Alps end.

The Vienna Woods to the west, the plain to the east, the Danube in between — and far enough north that the winter sun stays low.

Heights: Hermannskogel, the highest point of Vienna, and St Stephen’s Square

It climbs no higher than 18.4°.

On 21 June, at the same hour, it is 65.2°.

Block after block. Courtyards in between.

The Gründerzeit built Vienna densely. A 21-metre building casts a 63-metre shadow at noon in December — four lane widths.

Gründerzeit roofs of Vienna-Neubau on 21 December at 13:00, long shadows between the blocks

Image: Azima stage, Schrankgasse 10, 21 December 13:00 — calculated, not photographed

Sun above. Shade below.

The building opposite draws the line. Whoever lives above it has winter sun.

Facade on 21 December at 14:00: upper floors in sun, lower floors in the shadow of the building across

Image: Azima stage, 21 December 14:00

What only Azima shows

The sun in the room.

Sun maps stop at the facade. Azima keeps going: through the window, down to the floor, room by room.

Light report of the example flat Schrankgasse 10, 2nd floor: direct sun per room on 21 December, against the measured neighbouring buildings

Sun load map of the flat on 21 June at 13:05: warm colours where the sun heats the floor

Sun load per m² of floorlowmediumhighvery highrelative to the sunniest room of the flat, not a temperature

Sun load map of the flat, 21 June 13:05 — calculated in the browser, no upload, verifiable in the network tab

And in your Grätzl?

From 0.2 to 8 hours.

That is how long the sun shines on the street on 21 December — depending on the Grätzl.

Least

Burggasse0.2 h

Keplerplatz0.2 h

Währing Zentrum0.3 h

Most

Cottageviertel8.0 h

Hirschstetten8.0 h

Leopoldau8.0 h

Street level at the centre of each Grätzl, against the surrounding buildings (OpenStreetMap) and the terrain

How it is calculated

105,120 sun positions.

Every five minutes, for a whole year — against the roof model, the trees and the streets of the City of Vienna.

The data layers around Schrankgasse 10: roof model, trees, street lights, paving

232 661trees with height and crown

172 296street lights of the city

86buildings around the address

720paved surfaces around the address

220 × 220 m around Schrankgasse 10, every layer drawn from its file · data.wien.gv.at, CC BY 4.0

Calculated on your device.

Azima builds the house and its neighbours from the roof model as a 3D world in the browser and runs the sun over it — on the graphics card of your phone or laptop, without a server. The address goes to OpenStreetMap only for the neighbouring buildings; the floor plan never leaves the device.

And in summer?

Then light turns into heat.

Where Vienna is densely built, heat builds up into the night. Azima shows which room warms up in the afternoon.

Summer heat index per district (0–100), modelled from built form, green, street trees, water and elevation — not a measured temperature

Luckily, there is wind.

The west wind comes over the Vienna Woods. And on still summer nights cool air flows from the forest into the city — as far as Hietzing, Penzing, Ottakring and Hernals.

Mean wind in km/h at four stations (GeoSphere Austria) · night air: urban climate analysis of the City of Vienna 2020

The flat at Schrankgasse 10 on 21 December at 17:30, lamps on, the street in darkness

Which room wins at yours in winter?

Enter the address and floor, add the floor plan — and you see it per room, for 21 December as well as 21 June.

Check the light →

It calculates a clear sky. Against high fog, even the fourth floor does not help.

Sources Sun positions: astronomical (SunCalc) for 48.2° N, 21 June and 21 December 2026, Vienna time. Buildings: roof model LOD2.1 of the City of Vienna; trees: tree register; paving: road surface data (data.wien.gv.at, CC BY 4.0); OpenStreetMap. Rooms: light report of the example flat Schrankgasse 10, 2nd floor. Grätzl: street-level sun at each Grätzl centre against the surrounding buildings (OpenStreetMap) and the terrain. Heat: modelled index from built form, green, street trees, water and elevation — not a measured temperature. Wind: station means, GeoSphere Austria; night air: urban climate analysis of the City of Vienna 2020 (MA 18). One calculation, not an expert report.