Sand and ground temperatures

Sand and ground temperatures are even more extreme. During daytime, the sand temperature is extremely high: it can easily reach 80 °C or 176 °F or more.[18] A sand temperature of 83.5 °C (182.3 °F) has been recorded in Port Sudan.[18] Ground temperatures of 72 °C or 161.6 °F have been recorded in the Adrar of Mauritania and a value of 75 °C (167 °F) has been measured in Borkou, northern Chad.[18]

Due to lack of cloud cover and very low humidity, the desert usually has high diurnal temperature variations between days and nights. However, it is a myth that the nights are especially cold after extremely hot days in the Sahara.[citation needed] On average, nighttime temperatures tend to be 13–20 °C (23–36 °F) cooler than in the daytime. The smallest variations are found along the coastal regions due to high humidity and are often even lower than a 10 °C or 18 °F difference, while the large

st variations are found in inland desert areas where the humidity is the lowest, mainly in the southern Sahara. Still, it is true that winter nights can be cold, as it can drop to the freezing point and even below, especially in high-elevation areas.[clarification needed] The frequency of subfreezing winter nights in the Sahara is strongly influenced by the North Atlantic Oscillation (NAO), with warmer winter temperatures during negative NAO events and cooler winters with more frosts when the NAO is p

ositive.[19] This is because the weaker clockwise flow around the eastern side of the subtropical anticyclone during negative NAO winters, although too dry to produce more than negligible precipitation, does reduce the flow of dry, cold air from higher latitudes of Eurasia into the Sahara significantly.[20]