Je megla?

Ljubljana · Wednesday 28 October · 16:40

Cloudy.

Fairly sure · visibility 44 km

Tomorrow morning: more likely no fog. Mornings like this turn grey one time in three.

No fog, no sun. Ljubljana in power-saving mode.

Funny?
1500 m1000 m↑ 2.500 mTopol · 692 m9.6 °CPasja ravan · 1019 m7.8 °CKum · 1211 m7.3 °CKrvavec · 1742 m7.4 °CLjubljana · 11.6 °C
The basin at 16:40, squeezed sideways. Brnik: a few clouds from 2,500 m. Temperatures from ARSO's stations.

The fog's diary · 16:40 · RSS

Those clouds aren't mine. When I come, I'm lower.

— The fog

Fog in numbers

The numbers, fog or no fog.

44 km

of visibility. By the sensor you'd see as far as Grintovec (32 km), but not Triglav (63 km).

distances from the sensor in town; it can't tell what's in between

9 h

of fog last time: today from 01:00 to 10:10, with 20 min of sun in between.

fog or the lid, Ljubljana

−4.2 °C

That's how much colder it is on Krvavec (1742 m) than in town. The textbook says −9.4 °C: no inversion, but the air up there is warmer than it should be.

Ljubljana, 299 m: 11.6 °C, 11.6 °C by the textbookTopol, 692 m: 9.6 °C, 9.0 °C by the textbookPasja ravan, 1019 m: 7.8 °C, 6.9 °C by the textbookKum, 1211 m: 7.3 °C, 5.7 °C by the textbookKrvavec, 1742 m: 7.4 °C, 2.2 °C by the textbook2°4°6°8°10°12°Ljubljana 299Topol 692Pasja ravan 1019Kum 1211Krvavec 1742textbookmeasuredm

textbook: −6.5 °C per km of height · the hills are tens of kilometres apart

18 µg/m³

PM10 in town. Fairly clean air, for Ljubljana.

ARSO, hourly mean to 16:00 · Celovška 20 · daily limit 50

The last 24 hours

Nobody promised sun. It came anyway: 30 minutes.

10 km1 km200 msunfogvisibility 44 km18:0021:0000:0003:0006:0009:0012:00now
visibility in town (log scale)sun as ICON-D2 promised it yesterday at 16:44direct sun, measured

Escape plan

Where's the sun tomorrow?

The clouds are above every hill, from 2,500 m up. Running uphill won't help: even Krvavec is under them.

  • Rožnik 394 m45 min on foot from Prešeren Squareunder the clouds
  • Šmarna gora 669 m20 min to Tacen, then 1 h on footunder the clouds
  • Polhograjska Grmada 898 m25 min to Polhov Gradec, then 1 h 15 min on footunder the clouds
  • Krim 1107 m40 min to Rakitna, then 1 h on footunder the clouds
  • Kum 1211 m1 h 10 min by car, nearly to the topunder the clouds
  • Krvavec 1742 m40 min to the cable car, then 15 min upunder the clouds

Times are rough and assume no traffic. In fog there's always traffic.

The view from above

What it looks like from up there.

Meteosat's picture of the Ljubljana basin, less than an hour old.Ljubljana
Meteosat (MTG), 16:10. Colours as the eye sees them, every 10 minutes. White is cloud and fog. Contains EUMETSAT Meteosat data 2026.
Satellite image of the Ljubljana basin: white is fog and cloud, dark is hills and fields.Ljubljana
NASA Terra (MODIS), 27 October (yesterday). The mid-morning pass. White is fog and cloud; dark is the hills poking out. Today's comes once NASA has processed it, usually in the afternoon.
ARSO webcam, Krvavec, looking south
Krvavec → south. 16:40 · See the city lights? Then there's no fog.
ARSO webcam, Kum, looking north-west
Kum → north-west. 16:40
ARSO webcam, Pasja ravan, looking east
Pasja ravan → east. 16:40
ARSO webcam, Ljubljana, looking south
Ljubljana → south. 16:40

Season 2026/27

The score up to 26 October.

8fog days

3days without a minute of sun

1 daythe longest run without sun.

By 26 October, the 1950s averaged 15.2 fog days, the last ten seasons 11.4. Below average so far. Don't celebrate yet: December is coming.

On this day. On this day in 1949: day 1 of 12 in a row without a minute of sun. Fog on this date in 32 of 78 winters, most recently in 2025.

Our own count (fog from instruments, not a logbook) has run since 27 October 2026. Its first full day is today, if ARSO holds out till midnight, and it joins the count overnight.

Source: ARSO's log for Ljubljana, which runs a day or two behind.

Hall of shame

Ljubljana, ARSO's station at Bežigrad, October-to-March seasons since 1948/49.

Foggiest season
1951/52: 119 fog days out of 183.
Longest run without sun
22 days, three times, and each has a name now: the Advent Lid (1964), the Christmas Gloom (1973/74) and the New Year Dark (1997).
Least sun
1950/51: 279.8 hours of sun in six months.
Darkest November to January
1968/69: 69.9 hours of sun in three months.
The last 10 seasons
2017/18: 63 fog days and 73 without sun.
Least fog
35 days, in 2000/01, 2002/03 and 2004/05.

Was it worse back then? Yes.

An average October-to-March season, by decade.

fog daysof them, not a minute of sun

  1. 1950s: 94 fog days, 41 of them without a minute of sun.
  2. 1960s: 96 fog days, 42 of them without a minute of sun.
  3. 1970s: 74 fog days, 34 of them without a minute of sun.
  4. 1980s: 60 fog days, 20 of them without a minute of sun.
  5. 1990s: 45 fog days, 14 of them without a minute of sun.
  6. 2000s: 44 fog days, 13 of them without a minute of sun.
  7. 2010s: 54 fog days, 21 of them without a minute of sun.
  8. 2020s: 48 fog days, 10 of them without a minute of sun.
The 1950s had twice the fog days of today, and four times the days of fog without a minute of sun. It still feels like too many.

A fog day: the observer logged fog, fog with the sky visible, or ice fog.

A question

How many Ljubljana winters have you got behind you?

We count answers, not people. The author has more than 40.

Why we say so

  • Visibility in Ljubljana: 44 km.
  • Topol (692 m): above the fog.
  • Kum (1211 m): above the fog.
  • Krvavec (1742 m): above the fog.
  • Cloud cover: 8/8.

How we measure

Ljubljana every 10 minutes (ARSO's station at Bežigrad), Brnik every half hour, four hills from 692 to 1742 m, the ICON-D2 and ICON-EU forecasts, and Meteosat every 10 minutes. Every night we check whether the 10:00 call held, and the evening's bet on the morning.

The score shows after 5 foggy mornings. Until then, take our word for it, or don't.

Data: status.json · records.json · short