Thunder, lightning and rain headed to SLO County. Here’s when showers could start
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- Tropical Storm Mario will bring rain, thunder and wind to SLO County by Thursday.
- Forecasters expect up to a quarter-inch of rain, mainly in foothills and storm zones.
- Dry lightning remains a fire risk, though rainfall may reduce wildfire ignition chances.
Most of San Luis Obispo County could see thunderstorms, rain and high winds as the remnants of a tropical storm sweep through the region.
Tropical Storm Mario will move moisture to Southern California and the Central Coast late Wednesday through Friday, the National Weather Service said, leading to cooler temperatures and higher chances of thunder and lightning.
As of Tuesday afternoon, the tropical storm was about 700 miles off the coast of Los Angeles, according to Ryan Kittell, meteorologist for the National Weather Service.
Although the tropical storm will weaken as it barrels toward the Central Coast, there will be increased chances for precipitation and high humidity, Kittell said, resulting in sticky, muggy weather.
“Plan for extra time during commutes,” he told The Tribune. “Be aware of slick roadways, and if there are any thunderstorms, definitely stay aware and seek shelter if you hear thunder, see lightning or the winds are really increasing.”
Here’s the forecast in SLO County:
What’s in the weather forecast for San Luis Obispo?
The San Luis Obispo area was expected to be cloudy Wednesday morning with mostly sunny conditions later in the day, according to the National Weather Service’s latest seven-day forecast.
The high temperature was expected to reach 83 degrees, the weather service said.
Cloudy conditions will return Wednesday night with a 20% chance of rain after 11 p.m. The overnight low temperature will be 57 degrees, the weather service said.
A cluster of storm cells was still hovering over the Pacific Ocean as of Wednesday morning, according to a social media post from the National Weather Service’s Bay Area office.
The agency said it was observing the situation to see if isolated cells began forming over parts of California.
When will rain start in SLO?
On Thursday, skies are forecast to be cloudy with a 60% chance of showers and thunderstorms and a high temperature of 75 degrees.
The SLO area could receive between a 10th and a quarter-inch of rain, Kittell said, noting that higher amounts of precipitation are possible during thunderstorms, especially in foothill areas.
There’s a 50% chance of showers and thunderstorms Thursday evening, when the low will dip to 58 degrees, according to the weather service.
Retired PG&E meteorologist John Lindsey told The Tribune that most of SLO County will receive at least some rain Thursday with “a significant chance” for thunderstorms.
Dry lightning is possible, which could pose a risk for wildfires, he said, though there will likely be enough rain showers to staunch any possible sparks.
On Friday, there is a 40% chance of rainfall, the weather service said. Skies will be partly sunny with a high temperature of 74 degrees.
Friday evening is expected to be cloudy with a slight chance of rain before 11 p.m., the weather service said. The overnight low will be 59 degrees.
Dry and sunny conditions return Saturday when a high temperature of 78 is expected. The overnight temperature will dip to 59 degrees.
On Sunday, conditions will be mostly clear with a high near 82 and a low around 62 degrees, according to the National Weather Service.
How much rainfall will Paso Robles get?
The weather service’s latest forecast for Paso Robles calls for mostly sunny skies on Wednesday with wind gusts up to 15 mph.
The high temperature will be near 95 degrees, while the low temperature will be around 58 degrees.
Thursday will be mostly cloudy with a 50% chance of rain and thunderstorms and a high of 80 degrees.
The Paso Robles area could get up to a 10th of an inch of rain, the weather service said.
There will be a 50% of showers and thunderstorms Thursday night, which will be mostly cloudy with a low near 57 degrees.
More rain is possible Friday with cloudy conditions and a 40% chance of precipitation expected, the forecast said.
The high will be around 80 degrees while the overnight low will dip to 57 degrees.
Sunny weather will return on Saturday with a high of 87 degrees and a low of 56 degrees.
Sunday will be partly sunny with a high of 91 degrees and a low around 60 degrees, the weather service said.
This story was originally published September 17, 2025 at 7:00 AM.
