Het weer in Ljubljana in december

Ljubljana forum regulars keep December's forecast genuinely open both ways: could be a nice winter fairy-tale with snow and temperatures little below zero, or dull and rainy weather with temperatures little above zero, with more chance for rain than snow overall and recent years running lighter on snow than expected. Even a snow-free city visit isn't a loss — the hills and mountains will definitely have snow, and the Christmas Market, which starts at the beginning of December, is called a highlight regardless of what the sky does downtown. Roads get cleared fast when snow does fall, and rental cars come with winter tires by law, a genuine practical note for anyone driving. Our record: 5.5°C days, 0°C nights, 25.2cm of snow and 11 rain days — cold and genuinely wet, matching the “fairy-tale or dull and rainy, real chance of either” read.

Regulars are blunt that this counts as proverbially the worst month weather-wise here, genuinely impossible to predict - a beautiful sunny 15C spring day one visit, extended clouds and rain the next, with little advance warning either way. Our row backs that mild, genuinely wet read, 17.8C over 6.4C nights feeling 4C, with 95.2mm of rain across 8.3 days and a trace of very late snow, 5.1cm, matching regulars' sense that a cold snap can still arrive this late. Regulars are consistent that anyone staying several days has a decent shot at at least one or two genuinely good days even within an otherwise unstable stretch. Packing everything from a scarf and gloves to shorts is the standard, only half-joking, advice. The record: humidity 73 percent, 9.6 hours of sun, a 13.7 kph wind and AQI 44.

Regulars describe August here as hot with little rain and short storms here and there - the start of the month quite likely boiling, the end of it usually very pleasant. Our rain figures look like a contradiction until read together: 129.3mm is a large total, but it falls across only 8.2 days, about sixteen millimetres on each day it rains. That is the afternoon thunderstorm they describe, alpine and quick, worth an anorak rather than a change of plan, and it leaves the mornings free for walking. The row gives 28.7C reading as 31C at 74 percent humidity, over 16.7C nights. Their other warning is mosquitoes near water at dusk, the old town included. The record: 10.9 hours of sun and AQI 47.

Regulars treat the 1st of May as the traditional arrival of real spring here and rate the middle of the month above April for warmth. What they will not do is promise dry: expect at least some rain, they say, and carry a light jacket and a sweater under the umbrella. Our row is blunter still at 146.9mm across 13.4 days, which is a lot for a month described as fine - and they add that June is wetter again, with heavier rain but longer, warmer days. The compensation is the green: the city and its surroundings at their best, and the park spectacular once the flowers are out. Our figures: 21.2C over 10.6C, 9.8 hours of sun inside 15 of daylight, humidity 78 percent and AQI 47.

September in Ljubljana is a month that empties out and cools down, and regulars divide it firmly. The first fortnight is the one they recommend: around 25C and mostly sunny, with the August crowds gone and the sites quiet. Late September drops away quickly - lows near 8C, highs of 18 to 20 - and brings more rain than August, sometimes with cold air arriving from the north. Our row averages 22.9C over 12.4C with 183.1mm across 9.1 precipitation days, which is heavy rain on relatively few days. Their advice for either half is layers and a plan that survives a wet afternoon. The record: humidity 79 percent, 8.7 hours of sun and AQI 42.