A meteorologist shares the fall forecast for 2025. He explains which areas will transition to fall the quickest as well as what to expect with severe weather.
* An intense thunderstorm system brought rain and lightning to California's Coachella Valley.
* Dry lightning from these storms can spark wildfires, especially when vegetation is parched.
* Lightning is always dangerous, as the electrical discharge can travel for miles even without thunder.
* To stay safe, avoid plumbing and electrical equipment indoors and stay inside vehicles with windows closed.
An intense thunderstorm system moved into Southern California from northern Mexico on Tuesday morning, Sept. 2, bringing scattered rain and the potential for more storms throughout the day.
The National Weather Service expects the system to linger over the valley, though intensity could vary. Rainfall totals are forecast at one-tenth to a quarter inch.
The storm is part of the region's late-summer monsoon pattern, which can deliver bursts of heavy rain but also dangerous dry lightning. Across California, thousands of lightning strikes were reported, sparking several new wildfires.
In the Bay Area, an early morning storm produced a surge of dry lightning without rain or thunder -- leaving little warning for those in the area outside.
The system over the Coachella Valley is expected to linger in the region through the afternoon before an intense heat waves moves back in the region later this week, surging temperatures far above triple digits.
A flood watch will remain in effect through evening Wednesday, Sept. 3.
How does lightning form?
Lightning begins as static charges within a rain cloud. The storm cloud holds millions of tiny water droplets and ice crystals that bounce into each other by the turbulent winds inside the cloud. As they crash into each other, these droplets collide with other moisture that is condensing as it rises, creating a negative charge in the lower portion of the cloud.
Lightning flashes when the attraction between positive and negative charges becomes strong enough to overcome the air's high resistance to electrical flow.
A single bolt of lightning can heat the air around it to 54,000 degrees. Because of this high temperature, the air expands rapidly. The expansion generates a shock wave, which creates a booming sound wave, known as thunder.
What is dry lightning?
Dry lightning occurs during "dry thunderstorms," which produce little to no rainfall. According to the National Weather Service, the drier the storm and the drier the vegetation, the more likely lightning strikes are to spark wildfires. That's because cloud-to-ground lightning can easily ignite parched fuel without rain to help dampen it.
Is lightning without thunder still dangerous?
Lightning is always dangerous, even if unaccompanied by thunder or rain.
Thunder is simply the sound produced by the rapid expansion of air heated by lightning, according to the National Weather Service. If a lightning strike is far enough away, the sound may not reach you, but the electrical discharge can still travel for miles and ignite fires or injure people.
How often does lightning cause wildfires?
Lightning-caused wildfires are much larger and consume more land (53% of the average acreage burned from 2018 to 2022) than human-caused fires.
However, the majority of wildfires are caused by humans (89% of the average number of wildfires from 2018 to 2022).
How to stay safe around lightning
If indoors:
* Stay off corded phones, computers and other electrical equipment that puts you in direct contact with electricity, according to the NWS.
* Avoid plumbing, including sinks, baths, faucets and even toilets, if you can.
* Stay away from windows and doors, and stay off porches.
* Do not lie on concrere floors or lay against concrete walls.
If in a vehicle:
* Ensure all windows are fully closed.
* Refrain from touching radios, ignition systems, or any metal parts connected to the vehicle's exterior.
* Stay inside the vehicle until at least 30 minutes after the last sound of thunder.
What to do if a vehicle is struck by lightning
* Stay inside. Your car acts as a Faraday cage, directing the electricity around you and protecting you.
* Keep hands on your lap and away from metal surfaces.
* Do not touch the radio, dashboard, or any electrical components.
* Wait at least 30 minutes after the last thunder before exiting.
California wildfire map: New wildfires on Sept. 2, 2025
2-2 Fire
* County: Stanislaus
* Size: 300 acres
* Containment: 0%
Canal Fire
* County: Madera
* Size: 272 acres
* Containment: 20%
18-1 Fire
* County: Merced
* Size: 120 acres
* Containment: 0%
Salt 14-2 Fire
* County: Fresno
* Size: 60 acres
* Containment: 0%
2-3 Fire
* County: Calaveras
* Size: 30 acres
* Containment: 0%
25 Fire
* County: Stanislaus
* Size: 25 acres
* Containment: 0%
Rock Fire
* County: Sacramento
* Size: 25 acres
* Containment: 0%
Sierra Fire
* County: Placer
* Size: 25 acres
* Containment: 0%
Copper Fire
* County: Amador
* Size: 11 acres
* Containment: 0%
Air quality map in California
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Brandi D. Addison covers weather across the United States as the Weather Connect Reporter for the USA TODAY Network. She can be reached at [email protected].
Contributing: Janet Loehkre, USA TODAY