By Reginald Stanley. Posted September 7, 2026, 11:44 PM.

Tropical moisture from Hurricane Marie in the Pacific Ocean, coupled with an upper level trough from the Pacific Northwest, produced widespread rainfall and thunderstorms early this week across the region - in what was the first rains of the 2026-2027 water year across the majority of Southern California communities.

Increasingly cloudy, muggy, downright tropical weather descended upon Southern California over this Labor Day weekend. Rainfall and embedded thunderstorm activity was more focused to the north on Sunday, with especially heavy rainfall across Los Angeles County (with numerous cities breaking daily rainfall records). Precipitation dropped off significantly south of Los Angeles and San Bernardino, with San Diego County seeing only scant rainfall on Sunday. By Monday morning, dense storm activity over LA County had shifted south, producing scattered thunderstorms further south over Orange and Riverside counties. This activity sent waves of mostly light-to-moderate precipitation in a southwest-to-northeast direction, which included thunderstorms. Rain gradually tapered off during the afternoon and evening hours, with any remaining chances of showers and thunderstorms being confined to the mountains Tuesday and Wednesday.

Measurable precipitation was observed at all active WeatherCurrents stations, with two-day storm totals ranging from as high as 0.93 inches in Pinon Hills, to just 0.05 inches in South Fallbrook. In Temecula Valley's Wine Country, 0.24 inches was reported (courtesy of Jim Sappington); while 0.43 inches was reported in Riverside's Canyon Crest neighborhood (courtesy of Jim Ness). This storm was also notable in that it was preceded by a very quiet summer (monsoon-wise) across the region. A gradual cooling of temperatures is currently in the forecast for this upcoming weekend, although there is some uncertainty as to whether a trough from the Pacific Northwest will bring more notable relief from the heat, or a high pressure ridge prolonging the heat for a little longer.

Here are the rain totals for the WeatherCurrents network and associates: