Saudi Arabia: Annual rainy season underway across southwestern regions through end of September

Saudi Arabia's annual rainy season is underway through at least the end of September, bringing an elevated potential for flooding and landslides/mudslides to the southwestern regions.

Heavy downpours, flooding, and landslides could affect business, transport, and utility services in many areas. Localized disruptions could persist well after hazardous events have concluded; floodwaters may take days to subside, and debris from mudslides may take weeks to be cleared. Rural communities and informal settlements often sustain the greatest damage and casualties during such events due to poor infrastructure. Due to the arid nature of the region and poor stormwater management, even minor rainfall accumulations could quickly result in episodes of flash flooding. Flooding is possible in streams and dry riverbeds. Significant rainfall may be preceded by moderate winds and dust storms, though some areas - particularly desert areas - may experience high levels of dust without rain.

The risk of flooding is highest in low-lying communities near watercourses in recognized floodplains. Southwestern Saudi Arabia has several wadis, including the Al-Lith and Nu’man, that could flood during periods of intense rainfall. Flash floods, which can occur with little to no warning, often pose a threat to communities downstream of wadis, or dams in the event of structural failure. Urban flooding is possible in areas with poorly maintained or inadequate drainage systems, while storm surges may trigger flooding in coastal areas. Landslides and mudslides are possible in hilly and mountainous areas.

Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas, especially in rural areas, where infrastructure is already of a poor standard. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather could trigger flight delays and cancellations at domestic and international airports. Localized business disruptions may occur; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.