JEDDAH — The National Center for Meteorology (NCM) forecasts heavy thunderstorms across parts of Jazan, Asir and Al-Baha on Sunday, as a red alert for thick fog remains in effect across parts of the Eastern Province. The red alert covers Al-Ahsa, Al-Khobar, Dammam, Qatif, Buqayq and Ras Tanura from 12 a.m. to 9 a.m., with horizontal visibility expected to fall to 1 km or less. Moderate to heavy thunderstorms forecast over Jazan, Asir and Al-Baha could lead to flash floods and may be accompanied by hail and active winds stirring up dust and sand. Light to moderate thunderstorms are also forecast over parts of Madinah, while active surface winds stirring up dust and sand are expected over parts of Hail, Al-Qassim and the Northern Borders. Fog may also form during the night and early morning over parts of Makkah Region. For temperatures, Riyadh, Madinah, Dammam and Buraidah are forecast to record the highest temperatures at 42°C, followed by Makkah at 41°C. Hail and Arar are expected to reach 39°C, Jazan and Sakaka 37°C, Jeddah and Najran 36°C, Tabuk 35°C, Abha 30°C and Al-Baha 29°C. Humidity is forecast to reach 95 percent in Dammam, 90 percent in Jeddah, 80 percent in Jazan, 75 percent in Makkah, Abha and Al-Baha, and 70 percent in Tabuk. Humidity levels are expected to reach 50 percent in Madinah, Arar and Sakaka, 30 percent in Najran, 25 percent in Hail, and 20 percent in Riyadh and Buraidah.