Los Angeles’ dry season has not yet ended as rain has arrived ahead of schedule, bringing surprise to residents. On early Thursday morning, the greater Los Angeles area spanning four counties saw continuous rainfall, a rare occurrence that broke the dry spell of the past four to five months.
Around 4 am on Thursday, a large area ranging from Los Angeles County to Santa Barbara County witnessed unusual widespread rainfall. This was attributed to a moisture-laden system brought north by Tropical Storm Mario from the southern ocean, disrupting the prolonged drought period in the region. Meteorologists predict the storm will sweep across California, with Northern California expected to be affected by Friday.
Rainfall in the greater Los Angeles area this year has been notably abnormal. Several rain events in early May delayed the end of the rainy season by a few days, and a minor rain shower occurred on June 4. The mid-September rainfall this year is notably earlier compared to past years.
California’s Mediterranean climate is characterized by dry summers and wet winters. The water year in California starts on October 1st and ends on September 30th of the following year; the rainy season typically spans from October to April, with the bulk of rainfall occurring between December and February.
Ahead of the storm’s arrival, the National Weather Service issued warnings of the potential impacts of the remnants of Tropical Storm Mario, including the risk of wildfires sparked by lightning, flash floods, mudslides, and flooding in low-lying areas. The NWS warnings covered Southern California, Central California, and much of inland areas.
Flood warnings were issued by the NWS for parts of Los Angeles, Ventura, Riverside, and San Bernardino counties, expected to persist through late Thursday night.
Independent meteorologist Michael Mojarro pointed out on Thursday that the rainfall in the Coachella Valley and Palm Springs area is of particular concern, as the convergence of higher temperatures and strong winds at mountain tops could lead to thunderstorms persisting for hours in desert regions, bringing large hail, destructive winds, and a slight risk of small tornadoes.
By Thursday morning, rain had largely subsided in most areas of Los Angeles County. Rain continued in the Palm Springs area in Riverside County until the afternoon, with reports of thunderstorms alternating with sunlight around 2:30 pm; significant runoff was observed due to heavy rainfall.
Tourist hotspot Big Bear Lake and its vicinity were impacted by thunderstorms from noon on Thursday until around 5 pm. Radar estimates suggested rainfall of 2 to 3 inches in certain locations. Local flood warnings continued until 5:15 pm on Thursday afternoon.
Prior to the rain, Southern California was under a heatwave. While the rainfall brought some relief in temperatures, most areas, except coastal and mountain regions, remained hot after mid-morning. Cities like Temecula in eastern Los Angeles County still hovered around 81 degrees Fahrenheit by late Thursday evening. The combination of humidity and heat continued to make the weather feel muggy; forecasters indicated that the upcoming days of the week would resemble being in Florida.
Due to multiple wildfires affecting various parts of Southern California this year, there is a heightened risk of mudslides and landslides with the onset of rain. California Governor Newsom has directed multiple state departments, including the Governor’s Office of Emergency Services, Cal Fire, the Department of Transportation, and the California Highway Patrol, to ensure emergency personnel and resources are ready for deployment.
It is anticipated that another tropical cyclone may be brewing off the coast of Mexico, potentially bringing wet weather to California on Sunday and Monday of the following week.
Nancy Ward, Director of the California Office of Emergency Services, stated that California continues to face the dual threats of localized heavy rainfall and wildfires. The state government is working with local partners to ensure communities have the necessary resources and support to protect lives, property, and the environment.
The state government advises the public to remain vigilant. If thunder is heard, indicating lightning is close by, it is recommended to stay indoors if possible; if caught outdoors when a storm hits, seek shelter in large buildings or hardtop vehicles immediately, avoid open areas and tall objects, and refrain from seeking shelter under trees to prevent the risk of lightning strikes.