JEDDAH — Red alerts for heavy rain have been issued across parts of Jazan, Makkah and Al-Baha on Wednesday, as moderate to heavy thunderstorms capable of causing flash floods are forecast across several Saudi regions, according to the National Center for Meteorology (NCM). The red alerts warn of strong winds, near-zero horizontal visibility, hail, flash floods and thunderstorms. According to the NCM's Wednesday forecast, moderate to heavy thunderstorms accompanied by hail and active winds stirring up dust and sand are expected over parts of Jazan, Asir, Al-Baha and Makkah. Light to moderate rain is also expected over parts of Madinah, Hail, Tabuk, Al-Jouf, the Northern Borders, Riyadh and the Eastern Province. Fog may also form during the night and early morning over coastal parts of eastern and western Saudi Arabia. For temperatures, Makkah, Madinah and Dammam are forecast to record the highest temperatures at 39°C, followed by Riyadh and Buraidah at 37°C. Jeddah, Arar and Sakaka are expected to reach 36°C, followed by Jazan at 35°C, Tabuk and Hail at 34°C, Najran at 31°C, Abha at 25°C and Al-Baha at 24°C. Humidity is forecast to reach 100 percent in Dammam, 90 percent in Al-Baha, 85 percent in Jeddah, Abha and Jazan, 80 percent in Makkah, and 75 percent in Tabuk. Humidity levels are expected to reach 65 percent in Hail, 60 percent in Sakaka, 50 percent in Madinah and Arar, 40 percent in Riyadh and Najran, and 35 percent in Buraidah.