It wasn’t a drenching atmospheric river. But the biggest storm to hit the Bay Area in roughly 7 months began to douse much of California on Monday afternoon, slowing motorists, dropping snow in the Sierra Nevada, and providing a clear signal that the winter rainy season has begun.

The rainy season has officially started in the Bay Area as a storm is expected to bring nearly a month’s worth of rain to San Francisco in less than 24 hours, according to the National Weather Service.

Heavy rains from the remnants of Tropical Storm Priscilla caused significant flooding across parts of Arizona on Sunday. Here's what to expect.

The worst for the Shore will be flooding during high tides on Sunday afternoon and on Monday in the early morning and afternoon, while Philadelphia may only have minor tidal flooding.

We have long-term average high temperatures dropping at the fastest rate of any time in the year. We start this week with a long-term average high around 64 degrees. By this weekend the average high for the southern half of Michigan drops to the upper-50s. We are actually losing a degree a day on the average temperature.

The remnants of two tropical systems have drenched Colorado's high country since Friday, bringing more than six inches of rain to parts of the San Juan Mountains and prompting new flood alerts.

Some areas in Northern and Southern California could see a month's worth of rain by Tuesday, while the Sierra braces for several feet of early season snow.

Grab an umbrella — tropical moisture from the remnants of Hurricane Priscilla pushed into Arizona, bringing days of showers and cooler temperatures.