Why mercury rising over 40 in Muscat? Met explains SHARE Muscat: Oman’s met office on Monday explained why some wilayats in the Sultanate have been experiencing extreme temperatures for the last couple of days. A phenomenon called (foehn wind) was reported over the last two days in the Sultanate, causing the temperature to rise above 40 degrees Celsius during midnight in the governorate of Muscat. This happened when southwest winds blew from Wadi Samail, a mountainous area, to the coastal areas of the Sea of Oman (Muscat Governorate). The foehn wind happens due to a change from wet and cold conditions on one side of a mountain to warmer and drier conditions on the other (leeward) side.