Eritrea has two main climate zones, with a hot, dry desert strip along the eastern coast and cooler, wetter weather in the western highlands. The lowland regions between these extremes tend to be semi-arid.
The eastern lowlands and coastal belt experience a hot summer season, between June and September, when temperatures range uncomfortably between 86°F and 102°F (30°C and 39°C), and a cooler winter season, between October and May, when temperatures range between 77°F and 89°F (25°C and 32°C). The coastal belt gets some rain between October and March, but not enough to hinder travel. In the Dankalia desert region it gets unbearably hot and hardly any rain falls.
The western highlands are generally cooler and wetter, with an average annual temperature of 64°F (18°C). May is the hottest month of summer, with temperatures reaching 86°F (30°C), and the coldest winter months, between December and February, see temperatures dropping almost to freezing point at night. June to September is the rainy season in the highlands.
Asmara, in central Eritrea, has a pleasant climate year-round, with an average annual temperature of 60°F (16°C), with most rain falling between June and September.
The best time to visit Eritrea is either in September and October, or March and April. The period between June and September is best avoided because it is rainy in the west, and uncomfortably hot in the east.