Map from Google - Libya

In Libya the climate is Mediterranean in the thin coastal strip, and desert in the interior. As a matter of fact, although on the coast the temperatures are typical of the Mediterranean climate, the rainfall level is very low, semi-desert in Tripolitania and Cirenaica, and desert in the Gulf of Sidra (or Sirte). Only in the hills near the coast of Cyrenaica (called Jebel Akhdar), precipitation goes from 400 to 700 millimetres (16 to 27.5 inches) per year, so that they are covered by a Maquis shrubland.
Along the coast, which is the only plain area that receives non-sporadic rains, most of the rainfall occurs from October to early April, with a peak in December and January. The amount is usually low: between 200 and 350 mm (8 and 14 in) per year in Tripolitania and Cyrenaica, between 100 and 200 mm (4 and 8 in) in the Gulf of Sirte (which becomes definitely desert in the southernmost part), while to the east of Cyrenaica, in the easternmost part of the coast, on the border with Egypt (see Tobruk), it drops again to around 100 mm (4 in). The rains on the coast are due to the passage of depressions coming from the Atlantic Ocean or the Mediterranean Sea, and they alternate with long periods of good weather even in winter; since the period in which the rain can fall is limited, in some years a decrease in the winter rainfall may cause droughts, whose effects are felt until the following autumn.
In summer, the sun shines and it almost never rains throughout Libya, although in the southern part of the desert, some showers may occur, due to the African monsoon, which affects the Sahel region in the warmest months, and whose extreme offshoots can sometimes arrive here. Along the coast, air humidity is high, though sea breezes blow in the afternoon, relieving the heat. In reality, in summer the northern winds blow even at high altitude, because they are due to the baric configuration of the region, with an high pressure system over the western part of the Mediterranean, and a low pressure system on the eastern side, and that's why the Libyan desert is less hot than the Algerian desert. The average maximum temperature in summer goes from 30 °C (86 °F) along the coast, to 35/37 °C (95/99 °F) in the north-central inland area, to 40/41 °C (104/406 °F) in the south.

Libyan desert

Throughout the year, but more often in spring and autumn, Libya may be affected by the Ghibli, a hot and dry wind, which is able to raise dust and cause sudden increases in temperature; the phenomenon is even more evident along the coast, where it also produces a sudden drop in relative humidity, which is generally high due to the influence of the sea. In these cases, the temperature can exceed 40 °C (104 °F) from April to October, even on the coast, while in winter it can touch 30 °C (86 °F).

The main Libyan cities located on the coast (Tripoli, Benghazi, Misrata) have a Mediterranean climate, with mild and quite rainy winters, and hot and sunny summers, with highs in July and August of around 32 °C (90 °F) in the western part (see Tripoli, Al Khums), and 30 °C (86 °F) in the central and eastern parts, which are more affected by the northern winds that blow in summer in the eastern Mediterranean.
Here are the average temperatures of Tripoli.
Average temperatures - Tripoli
Min (°C)91011141720222321181310
Max (°C)181921242730323331282319
Min (°F)485052576368727370645550
Max (°F)646670758186909188827366

Tripoli, located in the western part, is the rainiest city, with 330 millimetres (13 inches) of rain per year, and a peak of 60/70 mm (2.4/2.8 in) per month between November and January; in Benghazi, rainfall amounts to 260 mm (10.2 in) per year, while in Misrata, near the dry Gulf of Sirte, it amounts to just 190 mm (7.5 in); in Sirte, in the gulf of the same name, it's about 180 mm (7 in), and in Tobruk, located in the east, it drops to only 110 mm (4.3 in).
Here is the average precipitation in Tripoli.
Average precipitation - Tripoli
Prec. (mm)60303015511015456070335

The sea temperature in Libya is warm enough for swimming from July to October, while it is a bit cool in June and November.
Sea temperature - Tripoli
Sea (°C)171616171922252726242219
Sea (°F)636161636672778179757266

Proceeding inland, the summer temperature increases quite rapidly: already at the Tripoli International Airport, 25 kilometres (15 miles) from the coast, highs in July and August rise to 35 °C (95 °F), and in el-Azizia to 37 °C (99 °F); the latter has been wrongly believed to be the hottest place in the world, due an incorrect measurement carried out in 1922.
A special case is represented by Bayda, located at 600 metres (2,000 feet) above sea level, on the hills of Cyrenaica, which receives 540 mm (21 in) of rain per year, and in winter, due to altitude, during cold waves it can even know the snow. Here is the average precipitation in Bayda.
Average precipitation - Bayda
Prec. (mm)1208560307211125560110544

In Bayda, the daily average temperature goes from 10 °C (50 °F) in January and February, to 23.5 °C (74 °F) in August.
Average temperatures - Bayda
Min (°C)66810141718181715118
Max (°C)141518222630292928262117
Min (°F)434346505763646463595246
Max (°F)575964727986848482797063

South of Tripoli, there is a mountain range, the Nafusa Mountains, where there are some cities located at an altitude of almost 1,000 metres (3,300 feet), such as Nalut, Zintan, Lefren, Gharyan, which in winter are slightly colder than the same Bayda.

Snow in Bayda

In the vast desert region of Libya, sunshine prevails throughout the year. During winter, the temperature range is high, so that nights are cold (the temperature can also drop to around freezing, and even a few degrees below in the north-central part), while days are pleasant, around 20 °C (68 °F). The daytime temperature exceeds 30 °C (86 °F) from April to October. In summer, the highest recorded temperatures are around 50 °C (122 °F). The rains are very scarce and sporadic, in the form of downpours: some areas can see no rain for years. The desert is almost everywhere uninhabited, except near the oases, which are fed by springs of water emerging from underground, such as the oases of Kufra and Sabha.
Average temperatures - Sabha
Min (°C)571116202423232117116
Max (°C)192226323639383836312520
Min (°F)414552616875737370635243
Max (°F)667279909710210010097887768

When to go

While waiting for the conditions of the country to be normalized, we can give some indication on the best period as regards the climate. To visit Tripoli, Benghazi and the main northern cities, you can choose spring and autumn, and in particular from mid-March to mid-April and from mid-October to mid-November.
To visit the desert areas, you can choose the winter, from December to February, keeping in mind that it can get cold at night.
The bathing season runs from mid-May to mid-October, although as we have seen the sea begins to be warm in July.

What to pack

In winter: in Tripoli and the coast, spring/autumn clothes, jacket and sweater, raincoat or umbrella. In the desert, spring/autumn clothes, light for the day, scarf for the wind-borne sand and dust, sweater, wind jacket, warm jacket for the night. In Bayda and the Nafusa Mountains, it's better to add some warm clothes, sweater or fleece, down jacket.

In summer: in general, loose fitting, light-coloured clothing, light and long shirt and pants, a wide-brimmed hat, a light scarf, sunglasses (even graduated instead of contact lenses), comfortable and breathable shoes; for women it is best to avoid shorts and miniskirts. On the coast, a light sweatshirt for the evening; in the desert, a sweatshirt for the night, sleeping bag for overnight stays, desert boots or sandals.