SAN FRANCISCO (CBS SF) — For much of the country showers in May are a commonplace occurrence, but not so much when it comes to the San Francisco Bay Area.

A rare spring storm front rolled into the region on Monday and dumped more than a inch of rain at the higher elevations. The National Weather Service said since the front moved in Mt. Tamalpais in Marin County had gotten over an inch of rain, Venado had received nearly 1.5 inches and Cazadero in Sonoma County about an inch.

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The culprit was a low pressure system that was parked off the Oregon coast and spinning waves of showers into Northern California.

“Look for precipitation to diminish this afternoon and evening over he region before another renewed chance returns to the North Bay and as far south as the Santa Cruz Mountains on Wednesday,” weather service forecasters said. “Isolated showers may persist into Thursday across the North Bay as the aforementioned mid/upper level low lingers off of the Pacific Northwest coast.”

While rare May showers traditionally have caused numerous problems in the morning commute with most of Bay Area residents sheltering in place, traffic was moving without any major issues.

And the wet conditions are not done for the week.

“Additional rainfall through Thursday is forecast to range from 0.25-0.50″ in the North Bay, except locally up to an inch in the coastal hills,” forecasters said. “Elsewhere, additional rainfall amounts will be mostly less than a tenth of an inch except locally more in the Santa Cruz Mountains.”

And more will arrive over the weekend.

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“Longer range operational … guidance remains in good agreement with respect to another late season storm system returning to the region late in the upcoming weekend,” forecasters said. “Temperatures will turn cooler as well by Sunday with the potential for widespread precipitation in the form of rain showers. Showers will then linger into Monday and potentially Tuesday as a cold upper level trough digs southward and then inland over northern California.”