The climate of Djibouti is tropical desert on the coast and in the north, while it is semi-desert in the south-central highlands.
Along the coast, where Djibouti, the capital, is located, it's hot all year round.
During winter, from December to February, the temperature is high, around 29 °C (84 °F) during the day. The amount of sunshine is high, the rains are rare, and the air is moist, but the cool sea breeze blows.
Starting from March, the temperature gradually increases, and the heat becomes intense, especially in May, when the daytime temperature fluctuates around 35 °C (95 °F), with warm nights, and still with damp air.
In June, the summer begins, characterized by an intense but drier heat, especially in June and July, when a wind from the desert, called Khamsin often blows, which can lift dust and sand and reduce visibility. Summer continues until September with really high temperatures, often exceeding 40 °C (104 °F), while at night the temperatures remain around 30 °C (86 °F). On the coast, in the afternoon the sea breeze can lower the temperature, while increasing moisture. September is perhaps the worst month, as temperatures remain high but the atmosphere returns to be quiet and the humidity from the sea makes the heat oppressive. In October, the heat continues to be sultry, but the temperatures decrease a bit and become similar to those of May.
Here are the average temperatures of Djibouti City.
Djibouti - Average temperatures
Min (°C)222324252729313129262322
Max (°C)292930323539424137333129
Min (°F)727375778184888884797372
Max (°F)848486909510210810699918884

In Djibouti City, about 120 millimeters (4.7 inches) of rain fall per year: this value is typical of a desert climate. Here is the average precipitation.
Djibouti - Average precipitation

In Djibouti, the sun shines all year round, but especially in spring and autumn.
Djibouti - Sunshine

In the inland region, the climate is semi-desert in the south-central highlands, for instance in the Day Forest National Park, where there are hills and canyons reaching up to 1,700 meters (5,600 feet), or in southern cities such as Randa, Arta, Holl-Holl. In the north, Mount Moussa Ali, the highest peak of the country with its 2,000 meters (6,500 feet), is even desert. In fact, being affected by the monsoon of the Arabian Sea, the central and southern inland areas can receive some rain in the period from July to October, and also some additional rain in winter, from November to March. Showers are rare, but sometimes intense, so much so that the wadis, the riverbeds that remain dry for most of the year, can occasionally become streams and may overflow, creating landslides and floods, as occurred in November 1994, April 2004 and March 2013. In the central and southern highlands, annual rainfall ranges from 200 to 300 millimeters (8 to 12 inches).
Here is the average precipitation in Ali Sabieh, located in the south, at 700 meters (2,300 feet) above sea level.
Ali Sabieh - Average precipitation

The temperature decreases with altitude, though it remains pretty high even at 700 meters (2,300 feet). Here are the average temperatures in in Ali Sabieh.
Ali Sabieh - Average temperatures
Min (°C)171920222325262524211917
Max (°C)272830313336373731312928
Min (°F)636668727377797775706663
Max (°F)818286889197999988888482

In Djibouti, there is also a depression, where the salt lake Assal is found, at 150 meters (490 ft) below sea level. In the west, there is a larger saltwater lake, Lake Abbe.

Lake Assal

The sea in Djibouti is warm throughout the year, and in summer it becomes very warm: the water temperature ranges from 26/27 °C (79/81 °F) in winter to 29/31 °C (84/88 °F) in summer.
Djibouti - Sea temperature
Temp (°C)262627283031302930302827
Temp (°F)797981828688868486868281

Tropical cyclones

Every now and then, Djibouti can be affected by a tropical cyclone coming from the Arabian Sea, but more rarely and with less intensity than in Somalia and Yemen because cyclones tend to weaken when they reach the mainland or enter the Gulf of Aden. However, sometimes the remains of a cyclone can reach Djibouti, bringing heavy rains that can cause floods, as happened with Tropical Storm 1A in May 1984, and Cyclone Sagar in May 2018.
Cyclones form from May to December, and are more frequent at the beginning (May-June) and at the end (October-December) of the period.

Best Time

The best time to go to Djibouti runs from December to February, since it's the least hot of the year. November and March are generally acceptable months as well, although a bit hotter. The worst time is the long summer because of the scorching heat.
During the summer, the sea is so warm as to allow long dives in the reef, and bathing is also a way to escape the oppressive heat.

What to pack

In winter: on the coast, bring summer clothes, and possibly a light sweatshirt for the evening. When going to the reef, you can bring snorkeling equipment, including water shoes or rubber-soled shoes.
In inland areas, bring light clothes, a sun hat, a desert turban, hiking shoes, sunscreen, a sweatshirt for the evening. In the mountains, a sweatshirt and a light jacket for the evening.
It's better for women to avoid shorts and miniskirts.

In summer: on the coast, bring tropics-friendly, lightweight clothes. When going to the reef, you can bring snorkeling equipment, including water shoes or rubber-soled shoes.
In inland areas, bring lightweight clothes, of natural fabric (cotton or linen), a desert turban; possibly a light raincoat for the rain showers. In the mountains, a sweatshirt for the evening.
It's better for women to avoid shorts and miniskirts.