Lebanon is 200 km long and 50 wide, and rises from sea level to 3088 m at Qurnat as Sawda in about thirty kilometres. That gradient means the coast and the mountains are effectively two different countries in climate terms.
Spring, April to June
The best window. The coast is warm without humidity, the mountains are green and covered in wildflowers, the Baatara waterfall is running with snowmelt, and there is still snow on the high peaks for photographs. May and early June are close to perfect.
Summer, July and September
Hot and humid on the coast, with Beirut around 30 degrees and heavy air, but the mountain villages at 1200 to 1800 m are pleasant and this is where Lebanese families and the diaspora go. It is festival season: Baalbek, Byblos, Beiteddine and Batroun all run international music festivals in July and August, and the country is at its most social. It is also the busiest and most expensive period, and August is when returning emigrants fill every restaurant.
Autumn, late September to November
Warm sea, empty beaches, grape harvest in the Bekaa and clear light in the mountains. October is the quiet favourite of people who know the country.
Winter, December to March
Wet on the coast, with most of the annual rainfall between December and February, and snow above about 1400 m. Lebanon has six ski resorts, of which Mzaar Kfardebian is the largest with around 80 km of pistes at 1900 to 2465 m. The season runs from January to March and varies enormously with the year. The skiing is not alpine in scale but the setting, with the Mediterranean visible from the top station, is unusual.
The morning ski, afternoon swim
The claim is genuinely possible in March and early April, when the sea is around 18 degrees and there is still cover at Mzaar, an hour and a half apart. Whether 18 degree water counts as swimming is a matter of temperament.
Ramadan and holidays
Lebanon is roughly a third Christian and observes both calendars, so Christmas, Easter in two dates, Eid al-Fitr and Eid al-Adha are all public holidays. During Ramadan many restaurants stay open, unlike in neighbouring countries, but hours shift and the evening iftar atmosphere in Tripoli and Saida is worth seeing.
What the weather actually does
The coast has a Mediterranean pattern: no rain at all between June and September, and 800 to 900 mm concentrated in the winter months. Humidity in Beirut in August is the real complaint rather than the temperature. In the mountains the same storms fall as snow, and the difference between the coast and 1500 m on the same day is routinely twelve degrees.