The best time to visit is between November and February when the climate is mild with an average temperature of 23°C in Jeddah and 14°C in Riyadh. Summer is unpleasantly hot with daytime temperatures rising to 45° C or more from mid April till October, throughout the kingdom, and temperatures in some areas reaching 49°C (120°F). The Asir Mountains, however, should be visited before November and after February, as they are impregnable during winter due to fog.
Saudi Arabia is one of the driest countries in the world, with rainfall averaging less than 5 inches per year. Marked seasons, in the European or American sense, do not exist. The climate is principally determined by the southerly shift in wind patterns during the winter months that bring rain and cool weather. Other factors such as latitude, proximity to the sea and altitude of the place, also affect the climate.
Daytime temperatures in summer rise to 45°C or more from mid April till October, throughout the kingdom, and temperatures in some areas reach 49°C (120°F). In Riyadh the average temperatures range above 40° C in June, July and August. In winter, during December, January and February, the temperatures in the main cities comes down during the day to 20° C and at night to even below 10° C in some places in the central deserts. Winter temperatures drop below freezing point in the central and northern parts of the country and snow and ice sometimes occur in the higher elevations in the southwest. Thus winter is cooler with an average temperature of 23°C (74°F) in Jeddah and 14°C (58°F) in Riyadh.
In the coastal areas, it rains regularly though Riyadh isn’t blessed with frequent showers. In the Empty Quarter, the great southeastern sand desert, ten years may pass with no rain. The Asir Highlands in the south receive rainfall due to monsoon winds exceeding 255mm (10 inches) per year. Jeddah, on the shores of the Red Sea, has a hot and humid climate all year-round. Taif, on the other hand, and Abha, enjoy much more temperate weather.
In areas where there is little ground cover, especially in the eastern part of the country, a northwesterly wind blows for most of the summer months and whips up violent sandstorms. October to May is generally pleasant with cool nights and sunny days. Night temperatures in the coastal areas may dip into the 40°F. From April to November, on the other hand, temperatures are considerably higher and life without air-conditioning is unheard of.